is it a snail?

[Andrey Grodno]

An unknown creature lives near the ascillia. What is it?

 

[twentyleagues]

It's hard to be sure. Looks like a cerith nodulosum or knobby cerith. But if in doubt pull it or sump it.

 

[Andrey Grodno]

It is attached to a rock. It does not crawl. Now I will try to take a picture of its corolla through a microscope.

 

[Andrey Grodno]

 

[twentyleagues]

It is attached to a rock. It does not crawl. Now I will try to take a picture of its corolla through a microscope.

So if it's attached to the rock it's probably not a snail. Very hard to see it. The over all shape from the pic above and the "is it a snail" title is why I answered with cerith. But from that pic I'd say a bivalve of some sort. Again it's very hard to see. Being with tunicates would make sense as to a bivalve, no idea as to the fact though.

 

[Andrey Grodno]

This creature sat in one place for three months. Then today it fell off the fireplace and crawled. It's about two centimeters.

 

[ISpeakForTheSeas]

This creature sat in one place for three months. Then today it fell off the fireplace and crawled. It's about two centimeters.

It looks like it may be Turritriton labiosus (also known as Cymatium labiosum), though I don't know for sure.

If it is that species, then it is reportedly a mollusk predator (eating bivalves and possibly other snails) and a sea urchin predator that paralyzes it's prey with some kind of poison, so it'd be odd that it sat there for three months.