What is this?

So, I had to put my hands into the tank and move our Long Tentacle plate which was inching up on one of our open brains.
While I was working on the tank we notice a small round nodule type "thing." It looks to be greyish in color and apperas to have a mucous type slime coating. It is very difficult to see as it is in the middle of the tank under some rock. It appears to be stationary but rocking, probably with the flow. It also appears to have one eye like opening. It is about the size of a pencil eraser.
Any thoughts? I was thinking maybe an egg sac of some sort...

 

Hard to tell, is there anyway that you could upload a picture? It might be a sponge or some sort of tunicate...but without a pic ID will be a guess at best.

 

As Bruce stated, without seeing a picture, it seems to be some sort of tunicate or sponge, as tunicates have two openings where sponges don't.

 

Pic!!!!!

 

Ditto on the pic!!!! lol:smartass2