Orbea carnosa is a leafless perennial stem succulent. It multiplies by stolons branching off from the existing decumbent stem bases to form additional erect or ascending pale green stems. There are conspicuous fleshy and tooth-like, triangular protrusions or tubercles arrayed in vertical columns and spaced along the stems. The stems may be covered in purple blotches as in this picture.
Small fleshy flowers are produced in spring and summer. The corolla has a five-angled margin marked with small teeth at the angles. Additional teeth can be seen on the flower margin, halfway along some of the corolla sides. These additions are sometimes absent, the sides even being indented to sunken midpoints. The corolla surface is sometimes much more creamy yellow towards the central annulus surrounding the coronas. Colouring and shape indicate that this is probably O. carnosa subsp. keithii (White and Sloane, 1937).