Rainbow Fountain
The Rainbow ountain first appeared in 2003 as a sponsor reward. In return for signing up with sponsors players could earn coupons toward painting their pets and changing its species. At this time there were no restrictions on what species or color your pet could be painted. It is important to note this was before the introduction of pets like the Krawk or Draik, and the only color exclusive to the Lab Ray was Robot. The Rainbow Fountain was shut down within a few months, as is common for sponsor related Freebies.
Years later the Rainbow Fountain was re-introduced. This time there were certain restirctions on the colors you could paint your pet (The fountain will not allow you to paint your pet Robot, Royal, or MSP - even if you have a poogle.) and changing species was no longer an option. In order to gain access to the Rainbow Fountain you must complete a Quest for the Fountain Faerie.
Recently players have found an item called Flash of Rainbow Fountian Water while fishing in the Underwater Fishing caves. When used on your pet it will randomly paint it any color available for that species (except for Robot, Royal or MSP Poogle of course).