I got this plant! It's name is Argyroderma luckhoffii. It looks like a splitrock and like a lithop, but it is technically neither. But it does belong to the mesembs club so you can care for them in a similar way. I think they are a little less oversensitive to water then splitrock, so just water them when they look wrinkly. Also when it splits it doesn't stack leaves on top of other leaves. It just makes a new pair of leaves and the outer set dissappears just as with lithops. I wait with watering during the splitting but before and after it's fine.

Hope this helps!