2nd pic

[BlackDragon]

2nd pic they are only on the rocks

[iCam]

Hey. Just harmless pineapple sponges :)

[rshimek]

Hi,

These images are still too poor for definitive identification, but they do appear to be small calcareous sponges. These are common in reef tanks, and often appear in the first few weeks after a tank is set up and then generally gradually disappear thereafter.

[BlackDragon]

thanks for the help, they seam to be multyplying. I just had 2 and now I have 12 that I have seen.
Thanks

[rshimek]

Hi,

Yes, they seem to do well in some aquaria, for a while, at least. :D