The chalice is certainly damaged. The acans are receeding. Only thing that I can figure is something irritated them enough to cause the damage. Snails, shrimp, another coral, fish, I know I have had fish out of no where decide to bother a coral. Food left on them that irritated them. Any damage to the flesh, these both can be very sensitive and go bad.
I never give up, but if the recession continues on the chalice, frag it away carefully and with nice clean cuts. Dip them in lugols and revive for 5 minutes and place in a hospital tank. A small tank that has same water as main tank. Or just put in your sump with nice light and flow. If they get any brown jelly like substance, pull them immediately. It will go to other corals.
I have had success saving corals with this method and then using an antibiotic in a hospital tank for 4-6 hours. Basically let them sit in the antibiotic water for 6 hours then put them in a new tank (away from my more toxic corals). I probably had 5 of 7 regenerate and survive. I did this with trachys and favias mostly, but wouldn't hurt to try with chalices and acans. Note: this was after I had brown jelly on a couple of them.
