Hanazono kabuto 花園兜 is one of the most famous and peculiar Japanese Astrophytum cultivars. Some additional woolly areoles are produced on the ribs surface.
Scientific classification
Kingdom:Plantae
(unranked):Angiosperms
(unranked):Eudicots
(unranked):Core eudicots
Order:Caryophyllales
Family:Cactaceae
Genus:Astrophytum
Species:A. asterias
‘Hanazono’ is a cultivar, nursery produced.
From my collection
via Flickr https://flic.kr/p/2krh7Qg