Locked Iron Chest鍵のかかった鉄の宝箱

An old chest made from iron with heavy chains strung around it. It could be opened with the right key.
In-game description

What is Locked Iron Chest? Features and uses

Locked Iron Chest is a common item in Core Keeper (Placeables & furniture). It can be obtained from Fishing in The Forgotten Ruins (non-fish catches), Fishing in The Clay Caves (non-fish catches).

Locked Iron Chest key points (from the game data)

Best source: Fishing in The Forgotten Ruins (non-fish catches) — 2.3% chance per catch.
Sells to merchants for 28 Ancient Coins.

Calculated and summarized by this site from the game data (1.3.0.6).

What you get from salvaging Locked Iron Chest (Salvage and Repair Station)

Locked Iron Chest can be salvaged. Salvaging it gives the following items.

For each material, the amount is "amount used to craft × 0.49 (lower when durability is down, 0.3 at 0 durability) × the item's multiplier", and a fraction is the chance of one more (2.4 means 2, with a 40% chance of 3). The range is from 0 durability to full durability (items without durability always count as full). Scrap parts are a fixed number set by the item level. All items that can be salvaged are listed in salvaging.

How to get Locked Iron Chest (Fishing)

Fishing (2)

Source	Type	Biome	Amount	Chance
Fishing in The Forgotten Ruins (non-fish catches)	Fishing	The Forgotten Ruins	1	2.3%
Fishing in The Clay Caves (non-fish catches)	Fishing	The Clay Caves	1	0.92%

"Chance" is the chance to get at least one of this item per try (opening one chest, defeating one enemy, one catch). A "guaranteed group" is the group of a chest or boss from which exactly one item always drops; it does not mean this item always drops (the chance of it being picked from that group is shown in small text). Only items that always drop are marked "Guaranteed". Fishing means catches with a fishing rod, separate from enemy and boss drops. Calculated from the game's drop tables (Conf/Loot, 1.3.0.6) the same way the game rolls them.