Got some new lithops (left in main pic) was drawn to them because they look totally different than my several year old ones (on right)

I saw these dark brown lithops in a shop choking in a plastic pot full of purely organic material and i wanted to save them xd luckily the organic material was dry and i picked it all off their roots.

Some of these new ones are clearly holding way too much water lol but now they are in my bone dry 85% inorganic substrate i make just for lithops and other things like conophytums and pleiospilos. They must have all sighed in relief. Xd

But why is it these lithops don't look like the other ones i have? That they have just this little slit in the middle?

Anyone able to identify them?

Thanks.