Look quickly and you'd be forgiven for thinking that's a gecko eye. Lithops usually only shed their outer leaves in spring but these have started already.
The new leaves peeping through. Although it's more usual to see the leaf pair split all the way across, sometimes the first set of leaves on a very young plant are only a slit
A more normal-looking pair of lithops, I was worried because they were wrinkling because I wasn't expecting new leaves so soon but I was relieved when the one opened wider and I saw that it was just the new leaves emerging.
Once they look like this, you stop watering the plants and they will absorb the water contained in the old set of leaves because there should only ever be pair. If you overwater them, they can end up with more than one set, or they start splitting or rot.