Creepers are a relatively simple fungal life form. It's epidermis is a layer of dried and compacted plant matter that is given off as a waste product by the actual living part in the core of the creeper. It has no central nervous system, and simply walks towards the nearest living thing it can detect. Creepers explode both as a predator deterrent and a method of reproduction. Creepers reproduce through spores, and exploding is how they spread these spores.