Button blanks from wild mussels discarded into or along the river.
Date is a wild guess, though it hardly matters. These poor organisms may have died nearly 100 years ago. Found in the mid- 80's on the river at Meyer, IL.

This observation is for the small holes on this northern quahog. Not sure if the various shapes and sizes were all made by the same organism or by several.

Shell collected by my kids sometime in the past few years in Shirley Chisholm State Park off Jamaica Bay.

This was a fun puzzle we found in the woods at Glenmeal SF. It’s a Fomes fomentarius conk with a bunch of markings, eventually I figured out those are left by the radula of a snail / slug. Apparently you can identify some taxa (families? Genus?) by the pattern— anyone have an educated guess?

The smallest snail shell there ever was. 250x magnification from a sample of dust on the ground of a garage. It was the size of a pine or spruce pollen grain near it on the slide. Maybe 40-50 microns but I’m not good with microns. Possibly a test from a microbe.