It looks stressed. They should have a "fuzzy" appearance when happy.
What's your water parameters? What lighting are you using, how far is the fixture above the tank? How much flow do you have?
Algae growing from its tips may indicate tissue loss.
hydnophora are as much like SPS corals as they are to LPS and require much in the same water parameters. They can pack a strong sting to neighboring corals and must be kept a safe distance apart.
Keeping P04 and N03 at zero, alkalinity around 8dkh and stable.