Black growth on rock

[NedFlounders]

I've noticed this black stuff slowly growing on my rock in places. Any ideas?

 

[madweazl]

Looks like sponge

 

[Chibils]

They look like tunicates, which are also known as sea squirts.

They are harmless filter feeders that suck in water and filter out small food particles.

Sent from my VS985 4G using Tapatalk

 

[NedFlounders]

Looks like sponge

I think you are right. Googled black sponge and found plenty of matches. Which leads me to another question:

Why are so many sponges growing in my tank, sump, and overflow??

The black sponges are only on the rock. There are "white" sponges popping up on random rocks, frag bases, in the sump, and my overflow.

what's the dealio?

 

[Jah2707]

I have heard if you expose them to air you will kill them. In the past I have seen them take over zoas and other corals.

On a side note, my current tank has quite a bit of yellow and blue sponges. So far I really like the look of them, but if they start over taking corals we will have words.