They have Sonorsian like heads and a single eye. They have exposed ribs and small legs. They have long arms made of electricity. They have jet-like appendages on there backs that enable them to fly. Though only male Ribulons have the wings. Females do not.
Since Ribulons are the only living things on Energia, there isn't any food on the planet. For humans at least. Ribulons eat electricity, and only electricity. It fuels them and allows them to reach full power.
The first Ribulons died out 150,000,000 years ago. They were called Fips. Fips wer small little orbs with one eye and tiny electrical arms. They evolved into the Ribulons of today.