What is this ?

[mrpenguin]

Can anybody tell me what this is ? They are all white and seem as if there is a little hairy feather looking thing sticking out in the middle..... it is growing on the onderside of my rocks and also in my sump ... but they are very small in my sump ....... in the shade, bot in direct light at all.

Are they good or bad ?

Thanks

http://i13.photobucket.com/albums/a289/bigbluec/Aquarium/what-1.jpg

[rynon]

Sponges, good.

[nw2rfing]

i have those also, i believe they are a form of sponge... theyve been harmless to me, but maybe someone will chime in with a more definative answer

[JJ21]

harmless little sponges

[mrpenguin]

Thanks

so its oK for them to grow in the sump as well ?

Anybody knows how big they can get ?

[JJ21]

Yeah, they're just harmless little filter feeders doing their own thing. Not sure how big they can get though.

[greenbean36191]

That's about as big as they get.