The Brain Beast first appeared in Episode 4 (Tree Trunks) of Adventure Time with Finn and Jake, it's a brain creature that has snake limbs and a ruby gem on its back.
Brain Beast paper toy created by Paper Foldables.
Adventure Time - Snake Armed Ruby Brain Beast Papercraft [Download]
Map of the Brain Papercraft [Related Posts]
Futurama - Brain Slug Papercraft
Paper Totem - Brain Muchers
Krang Papercraft
Krang Papercraft 2