Twonkies are known for their toughness, as all of Goddard's weapons don't even affect the Twonkie. Like all comets, Twonkus 3 is icy, and about 1/10 the size of the moon. When passing Earth's orbit, impact with the atmosphere creates colorful rays in the "sky" similar to the aurora borealis, the northern lights.
The comet is mostly white as it is covered in a snow-like substance. It has many large rock formations, which are all colored gray or tan.
Twonkus 3 only appears in the special, double-length episode Attack of the Twonkies.