Mimics

A Mimic is an aggressive Hardmode enemy disguised as a Chest, appearing as the appropriate Chest type for the environment. Mimics will look exactly like Chests until approached, at which point they will chase the player.

Mimics take on the appearance of Chests that would normally be found in a given area: normal brown chests closer to the surface, gold chests found underground, Ice Chests in a Snow biome, and locked Shadow chests in The Underworld.

Mimics can be spawned by the player using the Chest Statue, but they will not drop any coins or items besides the Mimic Banner.

Note that mimics stylized after an Ice Chest will only drop ice-themed items (Flower of Frost, Frostbrand, Ice Bow, and Toy Sled).

Identifying

 * Real Chests will show up on the minimap, but mimics will not.
 * Spelunker Potion will not cause a Mimic to glow, but Hunter Potion will.
 * Mimics disguised as Gold Chests or Shadow Chests will not produce a sparkle animation as the real versions do.
 * In single-player, if a new Chest appears at any point in an area you know well, it is a Mimic. Naturally-occurring Chests are only placed at world creation.
 * Mimics may not line up perfectly with blocks, as normal Chests would.
 * Mimics spawned underwater will appear as Gold Chests, not Water Chests.
 * Real Chests will never be situated directly over any empty tile spaces. They will also never appear in front of background objects (such as Life Crystals), since real chests are background objects themselves.
 * Shooting a stationary disguised Mimic with a ranged attack will cause it to become active. Also, Minions, the Magnet Sphere, and most homing projectiles will direct fire at a disguised Mimic.
 * Name every Chest you come across. Hovering your mouse cursor over it will then display its name no matter how far away you are.

Trivia

 * Mimics first appeared in Dungeons & Dragons in 1977, and have appeared in countless RPGs since.
 * Chest statues, which spawn mimics, are sometimes generated on top of wires connected to a pressure plate from a trap. This can result in a mimic attacking and killing you early on in the game.