I believe your right Stichodactyla gigantea? According to the internet.
Non-adhesive verrucae on upper column blue to maroon, contrasting with yellowish, pinkish, tan, greenish-blue, or gray-green column. Are these really hard to keep and has anyone been able to do so? What is the best thing to feed him? And what are the warning signs that something is going bad? PLMK Thanks in advance for your help.