Ink Sac

An ink sac is an item dropped by a squid upon death used to create black dye, dark prismarine and book and quills.

Squid
A squid drops one to three ink sacs upon death. The maximum amount is increased by 1 per level of Looting, for a maximum of 1 to 6 with Looting III.

Fishing
Ink sacs can be obtained as a "junk" item from fishing. The Luck of the Sea enchantment decreases the chance.

Trading
Wandering traders sometimes sell 3 ink sacs for an emerald in Bedrock Edition.

Compound creation
An ink sac can be created from its base elements, using the compound creator.

Crafting ingredient
$$, ink sacs can be also used in banner patterns:

Dye

 * Each type of dark prismarine can be crafted using varying amounts of 8 prismarine shards.

Trading
Journeyman-level librarian villagers have a $2/3$ chance to buy five ink sacs for an emerald. They always offer the trade $$.

Signs
Ink sacs can be applied to signs to revert glowing text back to default.

ID