I'd please, black sponge? Good/bad?

[seashep]

I have what looks like a black sponge but I'm unsure. It's encrusting and I'm afraid it will smother. New growth is not black but I've been watching it spread an it turns black. Any ideas or recommendations is appreciated.

 

[Reefing102]

Definitely looks like a type of sponge. My experience is they grow and die back as food supply comes and goes. I wouldn’t be overly concerned personally.

 

[griss]

Definitely looks like a type of sponge. My experience is they grow and die back as food supply comes and goes. I wouldn’t be overly concerned personally.

Agree with this.

Where did you get your live rock from?

 

[seashep]

Agree with this.

Where did you get your live rock from?

Got the rock from my local shop. It's been in the tank for 10 years though.

 

[griss]

I’d be careful removing it. @Paul B had a different sponge that released toxins when he tried removing it.

@Timfish any thoughts on this sponge?

 

[Timfish]

It looks like an encrusting cryptic sponge, doesn't like direct or bright light. I wouldn't worry about it unless it is growing well in direct light. If you want to control it you can use steel straws to scrape it off and siphon it out.

 

[seashep]

I never thought of using a steel straw like that. Thanks for mentioning it and linking it. I've moved the rock away from others for now so I can keep an eye on it. Thanks again for the reply and idea.

 

[griss]

Tim is a genius

I never thought of using a steel straw like that. Thanks for mentioning it and linking it. I've moved the rock away from others for now so I can keep an eye on it. Thanks again for the reply and idea.

 

[Timfish]

I never thought of using a steel straw like that. Thanks for mentioning it and linking it. I've moved the rock away from others for now so I can keep an eye on it. Thanks again for the reply and idea.

I wouldn't bother moving the rock. Sponge cells have a fast mitosis or splitting rate, as little as 8 hours. It's in your tank and it's going to grow where it wants to grow. (An intriguing question is with such a fast reproduction rate why is their growth so limited or slow, why don't sponges take over a tank in weeks or months?) Looking at the first pic it looks like there's at least 4 colonies and maybe 5 or 6 and it looks like it's staying almost completely out of direct light.