What's the purpose of rats, mouce and mice on earth?

rats are great pets.
im not sure what a mouce is.
as for mice.. [IMG]http://www.roberdo.com/wp-content/ylanfareoyunu.JPG[/IMG]

[QUOTE=B-Low]To be your GOD

[IMG]http://i174.photobucket.com/albums/w116/gazisgood/Fantasia.jpg[/IMG][/QUOTE]

:oldlol:

[IMG]http://www.theworldsbestever.com/2007/12/17/giant-rat.jpg[/IMG]

[IMG]http://www.coasttocoastam.com/timages/page/Nutria112707a.jpg[/IMG]