Whitesloanea crassa:

This succulent member of the milkweed family from Somalia is famously shrouded in mystery. Only discovered in the wild 3 times, last in 1986, it’s said that this species is either extinct or carefully guarded by the local tribesmen. Once said to be a relative of the similarly cryptic Pseudolithos, this monotypic genus is now aligned with Duvalia and Huernia. Rarely offered, especially at this size and on its own roots.