Official Ninjago.com Description
WARNING! No worries, you are in the Underworld, so everything here is already dead.
Sooner or later, everything somes to the underworld, and when it does, everything is larger than life. For this reason, every animal in the underworld is giant. This makes Ninjago's largest fossil-colossal collection of creepy, crawly, flying, slithering, skull-and-bone creatures.