What's this?

[alexwolf]

looks like a sponge to me. I have some also.

[Ross]

Its sponge. Dont let it touch air or else it will die.

[SuperXdude]

I'll go with what they said. It's a good sign of life growing. I've got several spidering over my rocks.



X

[Tim Marvin]

Sponges, good for the tank.