What is this?

[newbie6295]

Hi, Can someone tell me what this is please? (the white fuzzy thing) there's 3 that i can see on there but that is the biggest.

 

[flower]

Hi,
They are little filter feeding sponges. They clean your water as it passes thru them...good to have.

 

[newbie6295]

Thank You

 

[bang guy]

Sycon Sponge.