Grub

A Grub is a type of monster that appear infrequently in and beyond. They are similar in appearance to Larry Jr. and can spawn alongside Larry Jr. or The Hollow in their respective boss rooms.

Grubs move around the room somewhat randomly until they line up with Isaac, after which they rapidly charge towards Isaac, similar to a Charger. Upon death, each of the Grub's segments will spawn a Maggot, Charger, or Spitty. Unlike Larry Jr. which requires each of its segments to be destroyed, as soon as one Grub segment is destroyed, the entire enemy will be destroyed.

Trivia

 * Because of its similar movement behavior and design to that of Larry Jr. (along with the fact that Grubs can spawn in a Larry Jr. boss room), Grubs are also known as "Larry Sr." by The Binding of Isaac community.