what is this? a mushroom?

so i have had this thing in my tank since i set it up. i got it on some live rock when i first set up the tank.
it was very small at first but it has since grown. right now its the size of a nickle (10p coin)
it closes up sometimes like an anemone so it makes me think that maybe it could be one, or a polyp of some sort.

at night it shrivels up and during the day its in full bloom

any ideas?


this is the best pic i could get. its purple in color and has a belly button looking thing in the middle (kinda like an anemone mouth as well) it also has smaller bumps around the body too. its kinda see though and when i look at the stem i cant see it attached to anything. then again its a very pore like rock.

 

looks maybe like a hairy shroom to me.

 

Looks like Rhodactis(hairy mushroom) to me!!!!

 

yah its got small little hairish things at the tip....like a polyp....

anymore ideas?
i really like it and want to know what it may be haha.

 

are they a good thing or bad?

any special requirements i need to do if it is a hairy mushroom?

 

+1 on the brown button polyp. Although you said it's purple, it sure looks brown to me. I have 2 colonies of these on my live rock.

It's kinda fuzzy (the picture). Any chance of getting a clearer one?

Here's a picture of my polyps:

http://i308.photobucket.com/albums/kk351/Reeron/db19bd26.jpg

Here's a picture of a hairy mushroom from DrsFosterSmith.com:

http://www.liveaquaria.com/product/prod_display.cfm?c=597 598 665&pcatid=665

 

maybe im color blind haha! he could be brown its just the rock he is on is mostly purple so it kinda all blends in

 

that was the best one i could get. its small and hard to zoom in that close without it going too blurry.

 

Does it look like either of the pics I posted links to?