i would put 1 teaspoon/gallon non iodized pure salt in a cup with some tank water.dissolve it and add it over a few hours time. do a lot of water changes
He is nose down in the bottom of the tank. The ailing fin has changed colour, from pinkish to greyish. We wait for the medicine to do it's work, and pray.
pics aren't enlarging can't really tell what you got, first pic looks like some zoa's but can't tell for sure.
Here are a few pics of some unknowns found on my live rock,Friend or Foe???