Do you remember the movie "Mars Attacks" in which a human head has been grafted to the body of a dog? The result was a bit shocking and a lot funny. The sight of "Coral Cactus" reminds me of that scene for some reason. This man-made plant is neither coral (there is coral color on some of them) nor cactus.
Rather, it's a graft of Euphorbia lactea crest (interesting article about euphorbia vs. cacti here.) atop Euphorbia neriifolia. These are usually sold potted with glued-together gravel mulch which isn't particularly good for the plant so they should be repotted after purchase.
That's actually been done to some of these.
When thinking of grafted cacti, my mind goes here first.
These are certainly interesting plants.
Have you grown one of these? Do you have strong feelings about them one way or another?