The thornback ray shares many physical characteristics with other rays, possessing a flattened, disc-shaped body with enlarged pectoral fins and a long, narrow tail approximately equal in length to its body. The dorsal surface of the body and tail is covered with small thorn-like projections that, after sexual maturity, thicken to form button-like structures known as bucklers. In juveniles and young adults, small thorns are present on the snout and scattered across parts of the dorsal surface. Some larger females may also develop thorns on the ventral side. Typically, between 21 and 25 large thorns extend in a row from the nape to the pectoral fin.

Colouration varies from light brown to grey and is marked with light and dark spots of varying sizes. The ventral surface is white, with the exception of the snout, which is grey.

Despite its common name, the thornback ray belongs to the skate family, as it lacks a venomous stinger and reproduces by laying eggs. The species is oviparous and deposits egg cases in shallow coastal waters over sandy or muddy substrates. Females may lay between 140 and 160 eggs per year. The egg cases are rectangular and oblong in shape and are distinguished by rigid horns at each corner. Embryonic development occurs entirely within the egg case, with nourishment provided by the yolk, and hatching typically occurs after four to six months.