Knowing where the recession is may help.
A few initial thoughts...
  • Coral mucus can damage these corals. I lost a large purple fungia when a pagoda coral stressed and released copious mucus that landed on and smothered the fungia.
  • If the recession is near the mouth... my orange cycloseris has had exposed skeleton several times after trying to eat asterina stars. It has always recovered from that on its own.


HTH,
Tom