Really! Although had many sexually reproduced lps, it gotta be a zillion to one shot that such free swmming/pelagic medusae(?) landed on the plug. Higher probability to find new growth on the rocks than Plug, imo.Looks like the coral either settled on a base like that or it was simply glued to it. Either way, I'd agree that it is probably a Scolymia species, though a better picture would be helpful.