Top picture shows Turbinicarpus alonsoi. It caused a furor in the cactus world,when it was discovered in 1996 by Glass and Arias, because of its striking flowers and its resemblance to an Ariocarpus.
T. alonsoi contains several alkaloids , among them pellotine which causes convulsions.
Bottom picture shows Gymnocactus subteraneus v. zaragosae. In its native habitat this species grows among tall grass. Through evolution it has grown a tall neck to enable it to compete for sunlight.
Pictures submitted my Amante Darmanin