(or, as I assume, "euphorbia decaryi v. robinsonii").
Euphorbia decaryi (two-handfuls of variations, but all with the wrinkly leaves (each 'leaf' measures roughly 2cm in length)) is a succulent endemic to Madagascar in the close uplands bordering discrete and finite coastal planes.
It is on the The International Union for Conservation of Nature’s Red List of Threatened Species, as it is being pillaged because of its uniqueness, rarity and the demand that leads people to grab it and sell it on the open market.
Fourteen years ago, I was blessed with a lovely specimen as a housewarming gift, and I cared for it as best I could for ten years. Whether due to my lack of understanding for how it should be cared, or the Northern climate in which I was living, it failed, and eventually died.
I recently found a person in Miami who has been propagating these tubular cluster plants, and I purchased it for mere pennies . . . .
Time will tell if I am able to keep this cluster alive for longer.