Just spotted this in my tank ( im new to saltwater with a 50 litre tank) is it aipitasia? Is it dangerous? Whats the best way to get rid of it? Whats a cheap way to get rid of it? It came in on a purple pin cusion urchin from my LFS. Currently only have bicolor blenny, cardinal fish, 2 hermit crabs, mushroom corals, zoas, GSP and lots lf macro algea

