Skull

Skulls are collectibles acquired by completing levels in a single life and under certain time limits in time trial mode. A bronze skull is awarded if the level is completed in a very lax time (long enough, in fact, that the challenge mostly consists in simply surviving throughout the level), and a slightly more challenging trial grants a gold skull. Since skulls contribute to 100% completion of the game, in the interest of players uninterested in speedrunning no explicit skull prize exists for harder time limits.

Skulls exist both in normal levels and boss fights.