Casket

A Casket is a wooden chest obtained primarily by big net fishing, or as drops from monsters. Caskets can be opened, and may contain various items, including Half keys and talismans.

Methods of obtaining caskets

 * Found via big net fishing.
 * Drops from monsters, such as Dagannoths and Rock crabs.
 * Possible reward from opening a Mystery box in Quiz Master random event.
 * Found during Treasure Trails when the clue requires you to dig somewhere.
 * Warning: If you get a Casket in the Wilderness, it is recommended not open it there. Wait until you are out of the Wilderness to open it.
 * Possible reward upon releasing each of the 4 platypi in the As a First Resort... quest. An oyster is also another reward.
 * Bought in the Grand Exchange, or trading with other players.
 * Obtained from Miscellania by putting money in the fishing area.

Rewards

 * Caskets found via big net fishing, or monster drops contain any of the following items:
 * 20-640 Coins
 * Gems
 * Loop half of a key
 * Tooth half of a key
 * Cosmic talisman
 * Chaos talisman
 * Nature talisman
 * Caskets found via treasure trails may contain another clue, or the reward.