Anyone seen this before?

[Possumcop]

This showed up in my tank and I’m not sure if it’s good or bad. Anyone know what it is?

 

[Flippers4pups]

Good question, never seen one before.

 

[Anthonyl]

Looks like a suction cup.. No clue

 

[DSC reef]

Looks like a mermaid wine glass (acetabularia) macroalgae

 

[ReefWeeds]

Agree with @DSC reef - looks like mermaid’s cup algae. Not invasive and actually pretty rare.

 

[KrisReef]

I would guess you started this tank with some live rock? I've seen that come is as a hitchhiker on Carribean live rock. The rock sprouted once or twice with this algae, and then it stopped.

 

[Muttley000]

Agree mermaids cup. I get a piece or two every few months. A keeper in my opinion.

 

[Possumcop]

I think mermaids cup is correct. Kinda cool! Maybe it will stick around or spread some. Thanks guys!