Astrophytum asterias is called the Sea Urchin Cactus or Sand Dollar Cactus for its low, rounded form resembling the Sea Urchin. These typically are small plants, but some of the largest specimens can reach 4-5 inches across. The bodies usually have 8 low ribs and varying degrees of white spotting, occasionally plants are completely devoid of spots. Normally, flowers are lemon yellow with red throats, but some plants have been found with nearly all red flowers. Plants are reported from the Rio Grande Plains of south Texas and the Mexican states of Tamaulipas and Nuevo Leon.