2 years later, i need an id...

[renogaw]

i've NEVER seen this thing before, in pics or other posts, or in my tank.
today i found it attached to my return pipe.
it's sorta shaped like a bike helmet. the shell is solid

 

[ophiura]

Its hard for me to tell from the pics. Is it a bivalve? Can you get a macro shot?

 

[renogaw]

not with my camera (well, with my knowledge of it)
it does not appear to be a bivalve though

 

[renogaw]

well...
i drained down my overflow area and this thing is nowhere to be found... i mean it's completely disappeared, i couldnt find it in my sump, anywhere.
now i'm really stumped!!! i was going to try to figure out how to do a macro shot and now it's not worth it

 

[ophiura]

A lot of the bivalves are remarkably motile. You can see them and then they can move off.

 

[cranberry]

What does the "fleshy" part look like?

 

[renogaw]

if you're talking about the black part, it was solid as well, but it was ridged.