My girlfriend picked up a hammer coral frag (the tiniest frag I have ever seen) and kept it for a day thinking she could surprise me with it. She did, but I asked her when she got it and I cringed. I immediatly drove it to my house and let it settle on the lowest part of the tank on top of a rock. Half of its skeleton was showing and it didnt look too happy. Rods food and ocean nutrition flakes are fed daily and it really perked up. It healed and the side that showed no life fully healed! I moved it up and recently glued it to my rockwork, and its fully open and fully extended! I think hammers can take a beating and are pretty hardy from my experience.