Unknown growth

[rkearles]

Does anyone have any idea what this is? Just noticed it in my tank. It’s a fish only tank. Kinda looks like a coral but I’ve never seen a black one. Just want to make sure it doesn’t hurt my fish

 

[rkearles]

This the best close up I can get.

 

[ISpeakForTheSeas]

This the best close up I can get.

I really can't say from the pic, but possibly a sponge? Regardless, it's almost certainly harmless to your fish, so I wouldn't worry there.