Weird brown algae or something on trochus

[Mariners]

hi everyone,
Noticed these brown spots on top of a couple trochus snails. Thought it was just brown algae so i scrubbed it a bit but it was still there. then i dipped some hydro peroxide on a paper towel to wipe and drench those spots--it just receded into crevice or pockmarks on snail shell. Help identify this and is it an issue?

 

[saltyfilmfolks]

#reefsquad
I want to suspect an animal.

 

[reeferfoxx]

If it didn't look like a monie on my screen, my guess is aiptasia?

 

[dbl]

Not saying it is because I don't think it is, but it does almost look like aiptasia.

 

[jsker]

It is tough to say.

 

[nova65ss]

Hard to tell but look up colonial hydroids.

 

[Mariners]

Thx for the input everyone, not sure if i should be concerned as its been on 2 snails awhile and i dont have issues w hydroids and aiptasia. I qt everything from fish to corals but i dont qt inverts. Ive had these trochus for 3 months and it has remained brown little spots without tentacles just puffy patches. I would hate to get rid of them tho, but should i?