Ability chunk

Ability chunks are a currency in Splatoon 2. They can be acquired from or as a reward from Salmon Run. They are used by Murch to add secondary abilities to gear.

Obtaining chunks
Ability chunks can be obtained from green capsules that are rewards in Salmon Run. Ordinary green capsules have a 40% chance to contain 2 abilty chuncks and a 10% to yield 4, while shiny green capsules guarantees 4 chunks. Gear rewards can also be exchanged for the abilities present on the given gear, turning those sub abilites into chunks.

Murch has the option to scrub any gear the player has, where the secondary abilities are "scrubbed" off and turned into chunks that the player obtains with the cost of cash or  cash exclusive to the. The player also gains chunks when rerolling gear, where the previous sub abilities are turned into chunks.

Adding abilities
Multiple chunks are required to add one of the secondary abilities to a piece of gear. For example, if the player is looking to add one secondary ability of Run Speed Up, they would need 10 Run Speed Up ability chunks. The amount of these chunks that are required rises, if the player wants to add an ability that matches the one already present as a sub on the selected gear.

Uses
Ability chunks are a more reliable method for acquiring the wanted sub ability, then re-rolling gear, or using drinks from the Crust Bucket. As ability chunks are a reliable method for acquiring sub abilities, they are often used for stacking abilities or getting abilities that are unlikely to appear in a re-roll.