Trip-wire bomb casing

                             Trip wire bombs are an archetype of bombs that explode upon being stepped on.

Taking 3 seconds to arm, trip wire bombs are highly deadly and are great for

A trip wire bomb.

setting up traps and luring enemies to their death.

Trivia

Although trip wire bombs are intended to be used against enemies, they will also explode if stepped on by civilians. Therefore, Ezio and his allies are the only people who, if they step on a trip wire bomb, won't trigger an explosion.
Trip wire bombs are also used as an ability in multiplayer but their explosion doesn't kill players but dazes them.