I've been trying to free up the round pots I use for sowing by transplanting the bigger seedlings into square pots I use for adult plants. It doesn't really make more room for them but the depth is changing from 5cm to 8,5cm which they like very much. And of course I can now use the free round pot to sow some more mesemb seeds. :)
I like how flat and pancake-like the seedlings are. This is my favorite lithops shape. I just hope these particular seedlings are not too flat (is it possible for a lithops to be too flat?).