Any Idea What This Is?

[SaltyScott]

Found this on my live rock today. Have never noticed it before and doesn't seem to be moving although we'll see if it's still there tomorrow .

Any ideas? I haven't added anything to the tank in over a month.

Probably about 1cm or less

 

[wchen9]

Asterina

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[SaltyScott]

He wasn't far from my zoas and they've been pissed lately. I've read that some species will nibble on coral so I took him out. Don't want to risk it, although there is probably more where that came from .