SPONGE?? Dead??

This is What i think is a sponge on a piece of LR i Just Bought. is it dead or alive??? what type of food does it need to grow if it is still alive???

in this same piece of live rock i got a small mantis shrimp it very rarley comes out, i think it is a haptosquilla trispinosa i cant get a picture of the damn thing its so illusive. its about an inch and a half long will this thing kill my peppermint shrimp???
Thanks Fellas;D

 

It's a sponge. I've got the same type in my tank but I don't have the slightest idea what the name of it is. Mine are different colors, some blueish green, some yellowish, some tan colored and I don't feed mine anything. They absorb nurtrients from the water, very beneficial, and I've found them to be very hardy. Yours looks fine to me. Mine look very similair and have looked that way for a long time. I don't know about the shrimp.

 

When the shrimp comes up missing then you know why. I dont feed any of my sponges either.

 

same as Jbaker Have fun with your sponge..It will stick to the rocks. When you want to relocate to another rock it will leave a piece on the old rock where it was attached to.

This is how you can multiply..