Two of the small pincushion-type cactus can be confused until they bloom. The Hen-and-Chickens Cactus (Echinocereus viridiflorus) below sports a yellow-green flower. The flower comes from the side or base. Its last name means green flower.
This pincushion type produces reddish blossoms from the top. It is the Pincushion Cactus (Coryphantha vivipara).
Walk with care. All blooms are cactus, probably Bigroot Pricklypear.