Way too much light! Way, way too much!
I'm not sure what you have your tank lit with, but you're cooking those guys. Move your fleshy LPS on the sand to partially shaded areas.
If that's skeleton exposed on what's left of that Trachy, then yes, that's algae. I don't see much hope for that guy with the state it's in I'm afraid.
The scoly is recoverable, but you certainly need to decrease the amount of light it's getting.