Image from Wikipedia, taken by Jon Hanson, in Thailand: https://en.wikipedia.org/wiki/Crown-of-thorns_starfish#/media/File:Crown_of_Thorns-jonhanson.jpg
But genetics DOES indicate that there are multiple "cryptic species" across this animal's wide range in the Indo-Pacific..
and the ANUS of course! That's the dark spot, probably surrounded by spines... this shot is nice because it not only shows off the papulae (the gills) but also the pedicellariae (the red tweezer like structures)
And the ORAL surface!
Strangely enough, the top surface of Acanthaster is remarkably well known but how many people have actually seen the ORAL surface where the mouth is???
In addition to the tube feet all converging at the mouth, you also see the oral spines projecting into the mouth itself!