@Australis, I noticed that you associated my seedling with Ceropegia.
I'm always confused about this genus and the many names/synonyms. From what I read Ceropegia is a 4-sided succulent. All the other pictures including here confirm this.
But my plant (when grown) has many sides (30 or so).
I've seen it listed as Trichocaulon annulatum and Hoodia pilifera subsp. annulata.
Just throwing this out there because none of the adult plants listed for the Ceropegia entry look like the plants this seedling will turn into.