I traded for this Dinteranthus wilmotianus: I already have one but who wouldn't jump at the chance of getting another? Dinteranthus are closely related to Lapidaria and found in very hot dry, semi-desert areas of Namibia and the Northern Cape and they are considered fairly tricky to grow although they are similar to Lithops.
Like most succulents, they are a highly variable species and although fairly different-looking, these are both the same species
Splitting open very slowly. Once the new leaves start showing, it's time to stop watering and allow the water in the outer leaves to be absorbed back into the plant as the new leaves swell and grow.
Dinteranthus also form clumps but they are very slow growers and usually make only one set of leaves a year, as you can see in the top picture. Sometimes there are two sets of leaves revealed as it splits open and this is how the plant forms clumps. I'll have to wait a little longer to see what's inside the bottom-pictured plant, though.