Black things like clove

[sticksreef]

Hi.

Can anyone id these? Looks like very small clovers on the frag plugs on my zoas. They spread and leave “roots” when spreading.

Thank you

 

[rkpetersen]

Yes, they're blue clove polyps.
An extremely annoying hitchhiker.
They will spread very fast and cover all available rock surfaces. And the back glass, if you let them.
I didn't do anything about them when I first saw them in one tank, and now they're everywhere.
Seriously, kill them with fire.