Ball nem, Mojano or other???

[Idaknow15]

Please can you help me ID these, they are teeny and on the back of a hermit shell so easy to remove if a pest.
they are however actually quite pretty and fluoresce under the lights at the edge of the oral plate.
Thanks in advance!!

 

[bradleym]

This is a ball anemone, I don't think there's anything to worry about with them.

 

[Chrisv.]

It's a ball anemone, but I have had different luck than Bradley: the ones I had were incredibly invasive and stung zoas to death. Aptasia caused fewer problems for me. There are many species though, so some of them are no doubt less of a problem than the species I had.

 

[MaxTremors]

Psuedocorynactis, which isn’t a anemone, it’s more closely related to a mushroom/coralimorph. I don’t really view these as pests.