Please ID this alien hitch hiker!

[carriej]

Seen this, almost had a heart attack. One of the main reasons (other than cost) I started with dry rock was to avoid pests lol; and I seem to have the weirdest stuff!

What is it?? It lives in a trapdoor.. Looks like a little garbage can with a lid. It's fleshy inside.. Is it some kind of mollusc? I have not a clue.. Its bright red.

What is this beast?!?!

It opens and closes it's door real fast.. I poked it a few times with my feeding tongs. CREEPY