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I've got ball anemones in various holes in my rocks and they have bright green spots on them when under very blue lighting. Larger ones look like a ring of green dots but if they're small enough it just looks like one big green spot.
I know some reefers consider them pests, but I personally like a little variety in my tank and I haven't had any issues with them yet.
EDIT: Based on your pictures I can't really tell what's in your tank, you'd need to get a closer look in order to properly determine if it is ball anemones or something else.
Also, while I haven't had ball anemones on coral, I have seen them attached to macro algae.