Leather corals rotting?

[beckson]

Hi guys I recently started noticed something happening to all of my leather corals! All of my LPs and sps have been looking better than ever however only my leathers are being affected by something? I suspected my African biscuit star so I removed him from the tank but I feel the problem is still getting worse now any ideas? Possible other pest? Fish are purple tang, white tail bristletooth tang, Talbots damsel, lyretail damsel, fire fish, pair of regular clowns, trio of dispar anthias and a sixline wrasse. Also a filamented wrasse somewhere that has mysteriously gone missing recently. Could it be my urchins? Or snails? I did catch my biscuit eating the bigger toadstool however I’m thinking it’s because it was already affected and dying. Any help is appreciated thanks guys!

 

[CoralB]

Not sure . What are your Parameters