Crate

A UNSC storage device, containing Gas Masks, Helmets, Boots, Body Armor, Equipment and Ammo Holster and Briefs and Socks for Marines.

Crates can not be destroyed however in Halo 3 you can break the lid off with a melee attack. However they dont contain anything.

These crates are seen throughout all the Halo games. It is also an editable object in Forge found under the "Scenery" tab.