Anyone know what this might be?

[Miquel]

Have four things grow out of my live rock and am wondering if anyone might know what they are called. If I can get my camera working Ill post a pic. They look like black duckbills growing off the rock. On the opening end, and yes these tend to open to feed and shut quickly like a clam when startled, there are fine short white tentacles. As time goes on they keep growing longer and seem to be popping up around the tank. Have no problem with them so far but am just wondering if anyone has seen these before and might know what they are called so I can research a bit

[denhay14]

A picture would help out a lot.