Grubs

Grubs are NPCs found trapped in glass jars throughout Hallownest. They talk in high-pitched babbles and cannot be spoken to or hit with the Dream Nail. The player character can free them by hitting the jar with their Nail, after which the Grub will burrow into the ground and return to the Grubfather.

Grubfather
The Grubfather is an elderly Grub found in the north-west corner of the Forgotten Crossroads. He will reward the player for each Grub found. There are 46 Grubs in total.

Trivia

 * Occasionally the player will come across a Grub Mimic trapped in a glass jar that will transform and become hostile when freed.
 * Upon receiving the final reward(s) from the Grubfather, if the player rests at a bench and returns, they will find the Grubfather has swallowed all of the Grubs and is laying engorged on the floor.
 * It is unknown whether this is a cruel act on the Grubfather's part or just a part of Grub biology. The achievement the player earns after turning in all Grubs is called "Metamorphosis," and the charm references a "Grubberfly," a creature never seen in Hallownest.
 * This may imply that the Grubs are simply larval stage for a butterfly- or moth-like creature.