Perhaps Chests Mod Wiki & Guide

Biome-themed chests spawn naturally in caves, on the surface, and in oceans depending on the biome—look for Normal and Sandstone chests in common areas, Coral chests underwater, and rarer variants like Molten and Void chests in hotter or distant dimensions. They're often hidden in caves and underground structures, so explore thoroughly.

A mimic will transform into an aggressive monster and attack you, so be prepared with weapons and armor before opening unfamiliar chests. You can defeat the mimic to obtain rare keys or other loot.

You can tame friendly mimics to follow you and carry items like a walking storage container. Once tamed, they'll sit when you command them and fight alongside you in combat.

Use the lock and key mechanic to secure your storage containers—you'll need to craft or find keys to lock chests and prevent other players or yourself from accidentally opening them. Locked chests require the matching key to open.