whats this thing, looks like a mushroom(the kind of mushroom from a garden)

this thing appeared while I was at work today, I have got no idea what it is, so let me know what it is and good or bad...thanks in advance for any help, 3reef rocks...

 

hard to say with that pic for me but could it be a little feather duster?

 

def. not a feather duster, its coming out of the rock and the whole white stalk is soft(its blowing around in the crrent) and the top is like a dome shape, kinda looks like its acting like a parachute and blowing the thing around, doesnt seem to be a worm or anything doesnt move on its own...but it literally appeared in hours, between 9 this morning and 3:30 this afternoon, which is awful fast for something thats half an inch long...oh and the picture blows up bigger if you maximize the window it opens up in, Im sure you already know but I figure I'll try to help so we can figure out what it is...

 

it could be a small mushroom and its just streaching out for light and its the stalk you can see , how long have you had the rock? have you moved it recently?

 

rocks been in for about 2 or 3 weeks, havent moved it, it was brown with a white stalk, it broke off in the current the other night though and ended up in my filter so maybe another one will grow out of there. so i geuss if it comes back ill make a more indepth search, thanks for the replys though, never thought it might be a mushroom, now im wishing it hadnt broken off, it is in lower area of the tank so that may be what was going on, its about a 1/2 inch off the sand...

 

Am guessing some kind of sponge that hitchhiked in on LR.

I have several different varities that look and act similar.

Some have spread to adjoining rocks. Nice microfauna inhabitant.

 

yeah, that seems more likely as it wasnt quite shaped like mushroom coral, if another comes back I'll let it alone, I wasnt gonna move this one just was in the wrong place and the current tore it off, now if I could only kill the single aptasia I have, I found one the other day and killed it and removed all remains, but one is in a hole and keeps recovering repeated maulings, Ill get it yet...I need a peppermint shrimp or two I geuss...