Euendolithic tunnels in flakes on the beach.

Images made through a microscope. All subject types.

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Macro_Cosmos
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Re: Euendolithic bacteria tunnels in phyllosilicate on the beach.

Post by Macro_Cosmos »

I'm definitely wrong, first thought was "coral maybe?"

Or really, it's just a drumstick! :)

micro_pix
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Location: Southampton, Hampshire, UK

Re: Euendolithic tunnels in phyllosilicate on the beach.

Post by micro_pix »

The last photo was taken using a 100x NeoSPlan objective, and are “tunnels” in to a thin flake. The view is looking through the transparent flake so the tunnels are coming towards you from the far external plane. The flake is probably under 60 microns thick and the tunnels are under 5 microns wide. The shape, size and the branching is very reminiscent of fungal hyphal growth. There have been documented examples of hyphal growth tunnels inside silicate mineral (feldspar) but apparently not to the extent of the tunnelling seen in these samples.

Mycorrhizal fungi live in symbiotic relationships with plants and trees, their hyphae spread from the plant’s roots in to the surrounding earth. The plant supplies the fungus with the carbohydrates it needs (the product of photosynthesis) and the fungus supplies the plant with trace elements and minerals - more efficiently than the plants root system can. This is an explanation why these fungi would possibly tunnel in to and digest inorganic structures like rocks, it gives access to elements like potassium and magnesium and makes them available to the plant.

If these tunnels are caused by hyphal growth then it would have happened while the mineral was in much larger pieces close to trees/plants, near the surface and these deposits have subsequently been washed in to the sea and broken in to tiny flakes.

That’s my latest thinking but it’s just speculation, hopefully I’ll get some answers from the sample that’s gone for analysis.

Dave
Last edited by micro_pix on Mon Sep 21, 2020 11:12 pm, edited 2 times in total.

micro_pix
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Re: Euendolithic tunnels in phyllosilicate on the beach.

Post by micro_pix »

I've already sent some samples off to a lab but I thought I'd try to see if I could detect any possible hyphal remains in these samples. Chitin, a constituent of the walls of fungal hyphae, fluoresces white under UV when stained with Calcofluor White. I have some Calcofluor White so I stained a sample and put it under UV on my fluorescence microscope, the results are below. Unfortunately there is chitin in the exoskeleton of arthropods and Calcofluor White has the same effect on cellulose in the cell walls of algae and plants, having said that not many things are small enough to get far down a tunnel less than 5 microns wide!
I used UV illumination and DAPO UV 20x 40X and 100X objectives the blue background is probably background fluorescence from the silicate.

Dave
UV (1 of 4).jpg
UV (4 of 4).jpg
UV (3 of 4).jpg
Last edited by micro_pix on Mon Sep 21, 2020 11:12 pm, edited 1 time in total.

iconoclastica
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Re: Euendolithic tunnels in phyllosilicate on the beach.

Post by iconoclastica »

micro_pix wrote:
Thu Sep 10, 2020 1:32 am
Here are some of the other finds - up to about 2mm - I don't know what the club/microphone shaped object is.
Dave,

I think is part of the skeleton of a sea-star, in Dorset probably Asterias rubens.

Wim
--- felix filicis ---

micro_pix
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Re: Euendolithic tunnels in phyllosilicate on the beach.

Post by micro_pix »

iconoclastica wrote:
Mon Sep 14, 2020 9:46 am

I think is part of the skeleton of a sea-star, in Dorset probably Asterias rubens.

Wim
Thanks for that Wim, I just found another one, I don’t think I would have ever worked that out!

Dave

Ken Ramos
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Re: Euendolithic tunnels in phyllosilicate on the beach.

Post by Ken Ramos »

Wonderful photographs. Who would have thought that you would find so much in a few grains of sand! :)

micro_pix
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Location: Southampton, Hampshire, UK

Re: Euendolithic tunnels in phyllosilicate on the beach.

Post by micro_pix »

Thanks Ken.

I'm on to theory No. 3 now, which is probably the best explanation of what I found..

I looked at quite a few samples of the small flakes and they nearly all showed the same phenomena, they looked just like mica...... layered, transparent when thin and very reflective and they could easily be perfectly cleaved in to thinner flakes. Here's a photo of what they look like in the sand.. for size reference the centre flake is just over 1mm.
nacre_1.jpg
It was only when I found a larger, thicker piece that gave me a clue as to what it was. The larger piece had a tiny bit of outer shell attached and looked very much like it was originally part of a bivalve shell. This larger piece could easily be cleaved in to similar thin flakes - which all showed the same tunneling phenomena.

The harbour to the west of the beach where the sand came from has some large commercial oyster beds. The inner lining of the oyster shell (mother of pearl) contains a layer called "nacre", this layer is made up of very thin layers of platelets of aragonite, a form of calcium carbonate. The platelets and layers are cemented with a protein substance which makes it very strong. The oysters in the commercial beds are vulnerable to fungal attack. The fungal hyphae penetrate the shell outer and the nacre layer and can kill the oyster or at least destroy its commercial value. Apparently the fungus continues growing in the shell after the death of the oyster.

Over time (possibly partly due to the action of the fungus) the proteins in the nacre break down, leaving the much weaker layered structure of aragonite platelets which contain the tunnel evidence of the fungal attack. The weakened shells are easily broken up and these tiny flakes that glisten in the sun are the remnants of those layers.

Dave
Last edited by micro_pix on Mon Sep 21, 2020 10:59 am, edited 3 times in total.

Pau
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Re: Euendolithic tunnels in flakes on the beach.

Post by Pau »

This would be a very different interpretation!

An easy test: put some of the selected flakes into HCl at 5% (concentration not critical). Because aragonite is Calcium carbonate it will dissolve with strong effervescence (CO2) while mica is acid resistant.
Pau

micro_pix
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Re: Euendolithic tunnels in flakes on the beach.

Post by micro_pix »

Thanks Pau,

I don’t have any HCl but I do have some 99.85% pure Ethanoic Acid (Glacial Acetic). Is this OK and what sort of concentration do you suggest?

Dave

Pau
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Re: Euendolithic tunnels in flakes on the beach.

Post by Pau »

Acetic will work to dissolve shells, it's well known as calcium carbonate remover in domestic cleaners (although I never used it at the lab as HCl is the standard in Geology for recognizing carbonates). HCl (muriatic) at around 20% is very common and inexpensive in general drugstores at least in Spain

I don't know the adequate concentration to show effervescence but I would try 10 to 20%, it's less strong than Hydrochloric.

(if not used to work with concentrated acids be careful, even a weak acid at high concentration is clearly dangerous. To make the dilution always put the acid inside the water and not the water over the acid and absolutely avoid directly smelling its vapors, I got anosmia for few months after doing it with a bottle of glacial acetic acid like yours when I was student. Lesson learnt :( )
Pau

micro_pix
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Re: Euendolithic tunnels in flakes on the beach.

Post by micro_pix »

Thanks Pau

I put a few flakes on a glass dish and as a control I also put some shell fragments and some quartz sand grains.

In 20% ethanoic acid the flakes and the shell fragments effervesced vigorously, the quartz sand grains didn’t so that does lend support to theory number 3.

There’s a link here to a paper about fungal attack on oysters.

https://link.springer.com/content/pdf/1 ... 050076.pdf

Dave

Pau
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Re: Euendolithic tunnels in flakes on the beach.

Post by Pau »

So now, if you still have access to the beach, you can look for these tunnels in more fresh oyster shells, a further observation is always welcome,

I'm really amazed with the mica-like look of the oyster nacre and its beautiful rendering in your pictures. Well done!
Pau

micro_pix
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Re: Euendolithic tunnels in flakes on the beach.

Post by micro_pix »

Thanks Pau,

I have a few photos here of the larger piece (1cm) that had a small area of outer shell attached but is well on the way to disintegration. Not only does this piece have some outer shell but it also has some of the prismatic calcite layer present. The beautiful colours that we see in the mother of pearl on the inside of the oyster shell are produced by the interaction of light with two layers of material, an outermost layer of Nacre and underneath that, a prismatic layer. Both layers are made of CaCO3 but the structures are very different. The nacre layer is Aragonite - very thin flat layers of horizontal platelets which are cemented together with proteins. The prismatic layer is calcite and made of vertically arranged (roughly five-sided) columns.

Here are two SEM images from the paper "Physical and Biological Determinants of the Fabrication of Molluscan Shell Microstructures" Published in "Frontiers in Marine Science" Author Antonio G. Checa © 2018 Checa. Made available under a Creative Commons Attribution licence (CC BY).
prismatic_Nacre.jpg

This is the piece of shell remnant that all of the following pictures are from. The image area is 5mm wide and you can see the piece of outer shell on the right hand edge. Sorry the photos aren't as pretty as the earlier ones but it's easier with a thin flake.

.5mm area.
shell.jpg

The next photo (50x objective) is my attempt to show the prismatic and nacre layers on this piece of shell. I have marked a few of the tops of the columns of the prismatic layer, you can just make it out, the Nacre layer builds in stepped layers to the right. The colours are only vivid when the prismatic layer is present, the nacre layer is transparent when thin but also partially reflective.
layers.jpg

Here is an area of the same piece of shell that clearly shows the hyphal tunnels in the nacre and the prismatic layer is still partly present to the left (20x objective) The hyphal tunnels do go through the prismatic layers too.
2020-09-24-19.23.jpg

Here you can see the outer shell and the brown (because of the fungal damage) nacre layers which will gradually disintegrate in to thin flakes and look like bits of mica in the sand.
layers4.jpg
Dave

Scarodactyl
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Re: Euendolithic tunnels in flakes on the beach.

Post by Scarodactyl »

This has been an awesome thread! I have a masters in geology and I didn't even question whether the pictured flakes were mica.

micro_pix
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Re: Euendolithic tunnels in flakes on the beach.

Post by micro_pix »

Scarodactyl wrote:
Thu Sep 24, 2020 5:36 pm
This has been an awesome thread! I have a masters in geology and I didn't even question whether the pictured flakes were mica.
It’s been an interesting project, I’ve learnt a fair bit about mica and oysters!

There may be more than a few examples of this being mistaken for mica, take the photo on the bottom of this page for instance - https://www.sandatlas.org/mica/ I have heard of Finistere Oysters so a quick search and I found that there are 17 hectares of oyster farms on the sea bed in this area!! It does look suspiciously like my “mica”. I may go and see for myself when I can get over to France.

Dave

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