Slugs

are the trademark summon of Tsunade, one of Konoha's legendary Sannin.

Overview
Slugs' offensive abilities involves shooting acid from their mouths, similar to the way toads use oil. For defending others the slugs have the ability to encapsulate themselves around an individual's entire body. This essentially makes them a big cushion for the person inside, protecting the person from physical collisions. Slugs have also been shown to be able to divide themselves into many smaller replicas, though this ability may be unique to Katsuyu due to her size. Katsuyu can also absorb chakra from its summoner and even control it to some extent, as shown when Tsunade transferred her own chakra to Katsuyu in order to heal the citizens of Konoha when.