Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Anobiidae
Subfamily: Dorcatominae
Genus: Caenocara
Common name: Puffball beetles.

Puffball beetles are small insects in the genus Caenocara. It is thought that most of its life cycle is spent in fungi that grow among the organic debris.

The 3mm hairy beetle below was photographed in decaying organic material on the surface of a worm farm.
Puffball Beetles Caenocara .JPG

A ventral view showing the appendages which fit into the beetle's body when disturbed.
Puffball Beetles Caenocara -001.JPG 

Thanks to Wikipedia for text and information: