What is this?

[Markxc]

Anyone have any idea what this is? I found it attached to the side of my torch when i was rearranging things. it seems to retract to movement but not light.

 

[Mike N]

Bivalve of some type.. harmless filter feeder

 

[ludnix]

I think it is a type of bivalve, given how it moves. Possibly a type of scallop or clam. I would keep it and leave it alone, it may survive for many years there. I think it would be unlikely to cause issues or spread rapidly.

 

[Markxc]

thanks guys. i was pretty freaked out when i saw it.