These can be pests and invade tanks. In my older Red Sea tank they did take over large parts of rocks. When I did a good cleanup (to remove Majano and also pulsing xenia that had taken over), I managed to get rid of most of them.
In my tank now I have four Majano and I intend to keep it that way. Luckily Aiptasia X seems to work on them, at least makes them smaller so they don’t split. The ones I have don’t split very often either, so I am hopeful I can keep them under control. Either way I think they look great under whites and blues and aren’t particularly vicious.
