Fishhook cactus

Fishhook cactus is a common name for any hook-spined species of the genera "Mammillaria", "Echinomastus" or "Sclerocactus". They are small cacti, usually growing up to 6-7 inches (20 cm) high, and are shaped similar to a barrel cactus. They are not to be confused with the fishhook barrel cactus ("Ferocactus wislizenii") of the Sonoran and Chihuahuan Deserts. The Fishhook cactus is a large category of around 150 species.
Good places to see "fishhook" "Mammillaria" are the Sonoran Desert on the U.S. - Mexico border, and the Mesa Verde National Park. Often found growing in desert and rocky locations.
Notable species.
The genus "Mammillaria" also contains "pincushion" and other cacti.