help anemone pest zoa

Small roundish soft thing sitting on a “nest” of tentacles similar to that of a nudibranch or bubble tip anemone, however they do not move freely and are stationed where they are, have not moved an inch in almost a week. I think Nudibranch is ruled out When I touch them they react and “extend”...

posted a while back when I had 2 of these on a rock. In the past 6 months I've upgraded the lighting . Since then 2 has turned into 20!!! I think maybe now it's easier to tell for sure what they are on the rock in my tank. Trying to find out for sure this way if there's an issue I can take care...