Could be Mojano but also looks to me like baby bubble tip anemone. In the right conditions these are great as they don’t need to be in bright light. But depends on how much you like anemone.
Maybe set up a little quarantine tank and put it in there till it grows and you can tell better.
If you want rid of mojano and have the stocking capacity then a bristle tail filefish is great, but once they have eaten them they tend not to do so well.