A friend of mine has a 145 gallon full reef. Nice set up complete with calcium reactor, MH
, chiller, timers, dosers, a 7" deep sand bed!!, nice sump system...the works in equipment. Tons of live rock and coral he had been building for a couple of years. Frogspawns, hammers, mushrooms, xenia, clams, tube anemones, bulb anemones, his skunk cleaner shrimp have many offspring floating around and even his astrae snails breed well. The fish are basic...blue tang, a damsel, percula clowns, gobies, etc.
His cat one day knocked the probe to the thermostat shutting off the chiller and it was a HOT day. The tank rose from 83 degrees to about 87 degrees in less than three hours. The fish did ok, but the coral were not happy. He lost half his coral. He didn't remove the skeletal remains of the coral. He just kept them as part of the structure of his reef just as in nature. A few months later, there's new growth on a frogspawn skeleton. A new frogspawn had started to grow on what was perceived as dead.
It only takes a smidgen or remnant of live tissue for it to grow. I do believe corals can lay dormant when needed as well. Sure it's all part of an instinctive survival tactic. There's a lot not yet known about coral so there's much room for discovery. This is why they are so easily propagated in captivity as well as able to successfully take hold of a new environment open to their population. Coral can reproduce in two methods...anemones included. They spawn like fish as well as split like cells. You can take a mushroom and carefully cut it into two, three, or four pieces and so long as the environment is healthy, they will heal and grow as individuals. All soft coral can be propagated by cutting, but as far as I know you cannot do that to an anemone. There are crabs that go around cutting up soft coral...may even eat some, but they are helping the coral reproduce by setting off these little pieces of coral into the drift. Starfish can also be propagated by cutting. Amazing, huh? I witnessed a starfish leg grow a new body. Now THAT was weird. LOL.
This makes me think of the medical value of coral. Some of the world's best medicines come from the chemical 'weapons' of other animals and their genetic capabilities. Imagine if we can grow back someone's arm or leg?
I did read your thread about the footloose clam. I think the water may not have been suitable or acclimation didn't go too well OR there was a sudden force. For a clam to lose it's foot, I would imagine the animal is too weak to hang on or the force of the fall tore the feet off. Either way, it may not heal.