I hate to say it, but I think these are not a natural coral, but a bamboo coral that is naturally beige in color, and that it has been dyed red/green. Another option is that they are not coral, but they are 'dragon blood jasper'. They do look fascinating, though. ONly way to find out, I think, is to sacrifice one in the name of 'bead research'. Break it in half, and see what it looks like.

There are quite a few items in this Etsy store that are misrepresented or very highly priced for what they are.