Astrophytum myriostigma 'Fukuryu'
This is a rare type with well defined ribs and raised warts in between.
This plant is a slow grower and doesn't like a lot of water. Give it a very well draining soil mix and water sparingly during the warm season, letting it dry thoroughly in between. Winter is it's resting season and it doesn't like any water during this time.
These are on the smaller side, in 2.5" pots.