The fat bulborb is very fat. It's fat because when other bulborbs find food it takes the food and eats it, it also eats the bulborb that obtained the food. It also eats anything it finds on the on the ground like plants, carcasses, feces, dirt, etc. The largest one ever recorded was 555,555,555,555,555,556,596,366 tons, and was so fat it could not walk anymore or breathe. When it crawled it dragged it's fat along the ground and squished anything it dragged over smaller creatures.
The biggest parasite ever found on top of one weighed 738,457,8 tons and was a emperor bublax. one SMALL fat bulborb can have over two million parasites in and out of it's body.