anyone know what this is?

[jessinator752]

are any of these things harmful? if so what do i need to do. i have both fish and corals in my tank and i don't want anything getting harmed. thanks for all the thoughts. this is my first saltwater tank and i'm a little worried of something going wrong.

[thedude]

I'll second Jose, by the picture and the description I'd say sponge.

Sponges aren't harmful and are beneficial filter feeding organisms. Occasionally you'll find an aggressive species that grows qucikly so just watch it to make sure it doesn't grow over your zoos.

John

[jessinator752]

ok, thank you so much for your help. i was a little worried as you can tell. here is a picture of my full tank if anyone is interested in seeing it. http://i131.photobucket.com/albums/p...2/fullview.jpg thanks again for all your ideas.

[safeuerwehr]

I have several sponges in my system, some are white, green, yellow, and even black...most have been very non aggressive but some the ones that came on a zoa rock had little spawns that had hair like needles on them which released and traveled all over the tank....then the mother colony started to grow and over take the zoas....so yeah i agree with thedude, just keep and eye out that they dint over take its host area..

Alfred