Alveopora. Can be a tough one depending on where it came from. Looks like someone dragged a colony though so it may have been in captivity for some time so you could be ok. Not as hard to keep as it used to be but still a tougher coral
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20 Gallon SPS reef
29 Gallon FW "fat catfish" tank
20 Gallon Long Dart Frogs "Zig" and "Zag"