Succulent Plant, Euphorbia Muirii
This plant has been very difficult to propagate. It likes less water than other succulents until the root system is very strong.
And, like with all euphorbias, if you contact any sap, do be sure to wash hands very well before touching anything (skin, clothes, eyes, pets). I've been growing euphorbias for a few years and have never had a problem, and many big nurseries sell many types of euphorbias, but it's worth noting that *some* people have a very strong allergic reaction to euphorbia sap--I've read of temporary but long-lasting blindness!