Do you know this beautifull cultivar ?
http://www.cactus-art.biz/schede/ASTROPHYTUM/Astrophytum_myriostigma/Astrophytum_myriostigma_hakuun/Astrophytum_myriostigma_hakuun.htm (http://www.cactus-art.biz/schede/ASTROPHYTUM/Astrophytum_myriostigma/Astrophytum_myriostigma_hakuun/Astrophytum_myriostigma_hakuun.htm)
not so rare, here in italy... =)
we are talking about it here:
https://www.cactuscultivars.com/forum/index.php?topic=524.0