If you mean sprites, then you'll find them all around. Heck, if you don't have 3d models on, you'll already be looking at one; Your character. A sprite is literally ANY 2d texture that isn't a part of the map geometry. Like, springs, spikes, stalagmites, players/enemies, you name it. They're even used for decoration! Heck, even WITH 3d models, they still look for the sprites they are supposed to replace!