The 12 to 15 radial spines are needle-shaped, bright, brown or white and up to 4 inches (10 cm) long.

The 1 to 3 central spines are longer and stronger, straight and curved like a hook at the tip.

The flowers are orange, dark yellow, magenta, or violet[3] with a red center, about 7 inches (18 cm) long.

[6] It usually grows in black or clay soils on coastal lowlands under mesquite scrubs, at an elevation of about 0–550 metres (0–1,804 ft) above sea level.

[7] Plants are found growing along Astrophytum asterias, Mammillaria heyderi, Echinocereus stramineus, Echinocereus poselgeri and Echinocactus texensis[8] In 1845 George Engelmann first described the plant as Echinocactus setispinus.The genus name "Theloocactus" derives from the Greek word "Thelo" (wart or nipple) referred to the ribs with closely spaced nipples, while the species name "setispinus" comes from the Latin “seta” meaning “bristle” and “spina” meaning “thorn, spine”.