Euphorbia milii aka Crown of Thorns:). Be careful this plant has a toxic white substance that leaks out when cut. So wear gloves and glasses when handling it.

Thank you so much!

I've been reading some info and thinking; isn't it somewhat negligent for a vendor to sell a poisonous succulent with no identification?

There are many, many poisonous things sold without ID...but, read this thread -click here please-

Serious! Thank you, I will be so careful and at least I know for a fact that I'm not allergic to latex. To think we don't allow Kinder eggs, but this is just fine ;)

Thanks! I would probably be worried if I had a cat, but it'll be fine for me :)

(Kinder eggs are a chocolate candy with a prize in the middle, sold in Europe and other countries besides the US that trust their citizens not to put the entire thing in their mouths and choke on it.)

All Euphorbias have toxic sap- no exceptions, though the amount of sap and the concentration of the sap varies from plant to plant... it is NOT highly toxic, however, unless ingested in large amounts (which is very difficult to do as it is irritating- few animals or people could ingest much). This species, being rather woody in consistency, is less likely to ooze it's sap on someone by simply bumping into it, though, as what often happens with the relatively soft-skinned 'pencil cactus'. As for cats and Euphorbias, pretty sure there is very little experience with toxicity in cats, as few if any cats would be crazy enough to eat a Euphorbia (would require a huge degree of pain tolerance, lack of finickiness and a lot of stubbornness, rare qualities in most cats).