Nothing Lasts Forever… Trophy

Each world in the game has a skull tooth level which you need to complete in order to collect the 10 skull teeth in the game, see "The Jaw!". Once you collect all 10 you unlock a bonus level that can be accessed from the Snoring Tree.

This is the hardest level in the game, and will likely take many attempts to get through each section. At the end of the level is a boss fight and finishing the level will get you this trophy. See below for a video of the level.