covered with crystals

[Litonotus]

simocephalus vetulus with crystals

[vasselle]

Very nice photo

[Olympusman]

I've been watching these crystal posts for some time, and the effect may be the same effect you would get if you cross-polarized a cassette or CD case. It might be stress signatures in whatever the material is that makes up the shell. Any ideas out there?

[Pau]

I've been watching these crystal posts for some time, and the effect may be the same effect you would get if you cross-polarized a cassette or CD case. It might be stress signatures in whatever the material is that makes up the shell. Any ideas out there?

The colors are interference colors produced when a birrefringent material is placed between crossed polarizers, its exact shape is dependat of the total birrefringence and orientation, but the cause of that birrefirngence is a bit different: in plastic, an amorphous material, it's due to the preferent orientation of the polymer molecules when stressed*. In true birrefringent crystals (all but the ones of the cubic system) it's due to the different RI in different directions because the anisotropic ordered structure.
The crystals on the exoesqueleton are naturally birrefringent, not stressed, maybe made of calcite or aragonite.

*a nice exercice is to pull a transparent plastic between polarizers while looking

[pwnell]

Excellent.

[Litonotus]

thank you (:

Yes, this one is taken using the CD "compensator".

[_Michal_]

Excellent photo!

[carlos.uruguay]

Nice!