The first is a polychaete trochophore. This bristle-worm larval stage is planktonic and known as a "trochophore". Very active. Here is a heads on view with electronic flash to stop the action.
Olympus 20/0.70 S Plan Apo. 2.5X NFK. Canon EOS R. DIC.

I posted a shot of a live foraminfer a week ago. But this one is shot using darkfield and shows the streaming ectoplasm that was not visible in the previous image.
Olympus 20/0.70 S Plan Apo. 2.5X NFK. Canon EOS R. Darkfield.

Pretty sure this is a Strombidium. Here it has one end resting against the cover slip. At rest like this they make an interesting pattern.
Olympus 60/1.40 S Plan Apo. 2.5X NFK. Canon EOS R. DIC.

These last three are diatoms from my plankton net. There was a real "bloom" of these diatoms but the slides were a completer jumble, so I looked around and found a few attractive scenes.


