What gives with hammer corals? Why so difficult?

[bnord]

Ditto on the hammers retracting when the lights go down, and the occasional expelling of brown snot from time to time. Nothing to worry about. Mine started as 2 heads 17 years ago.
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need to start a thread asking what I have to change in my chemistry to make my 7 week old hammers look like your 17 month old hammers... smile - and to the OP I agree they react more quickly to change in light, but so does one of my 5 torches - i.e., some population genetics result in different "behaviors"