Cryptanthus "Ruby" is a smaller growing Cryptanthus. This genus is in the Bromeliad family and is native to Brazil. It has bright green and red stripes in high light, but in low light turns almost fully green. The mature plant can reach about 7-10 inches in diameter. It grows moderately slowly in a vivarium and does best under very bright, indirect light with moderate humidity. Airflow is helpful. Moist soil and sphagnum moss are helpful for rooting this species, but it can root on many substrates. Do not let it sit in water.
Cryptanthus are sold in "pup" form and mature form. Many pups will not have roots, and will be smaller, usually 1/4 to 1/3 the size of a mature specimen.