Friend or foe

[MarkH81]

A couple of months ago I noticed what I though was a zoa polyp from a previous zoa growing on my rock work. There was a green circle that glowed under blue light like the zoas used to so I was quite happy to have it growing back. I thought nothing of it but to my surprise, a few more of the appeared on different rocks. On closer inspection, inside the green circle it looks clear and there looks like feeding tentacles surrounding it that retract when disturbed like an aptasia. I am now concerned that this might be more of a pest and will start to sting my other corals if there are feeding tentacles out but I can’t seem to find any information on them. Please help. Many thanks.

 

[Tahoe61]

I belive it might be a Ball Tip Anemone. Harmless ime, but others report that they can be invasive in heavily fed tanks. I never had an issue.

 

[MarkH81]

From googling photos of ball tip anemones, I’d say you’re spot on there. Good to know they’re harmless. Thanks very much.