The Rot is a recurring threat throughout most of Rain World.
It appears in two different forms:
"Daddy Long Legs" are composed of a mobile, irregularly-shaped, black core with brown, blue or purple highlights and multiple tentacles. They cannot see but have very good hearing and are drawn to most sounds. Upon contact with any organism the tentacles immediately draw it up into the core where it is consumed. There are very, very few sentient creatures in Rain World that don't fear Daddy Long Legs.
"Proto Long Legs" in comparison, are immobile. In areas where they can be found, they line the floor, walls and ceiling. While unable to pursue the player, they still consume anything which comes in contact with them.
The Rot is visually and behaviorally unusual compared to all other life forms in the game. It's origin is initially unknown.
It is produced when an Iterator meddles with its core programming. Iterators have a substantial microbial component (either biotechnological or nanotechnological), which is capable of self-replication. As a consequence "meddling with its core programming" amounts to modifying its "DNA". If the process goes awry, it can easily lead to uncontrolled mutation, loss of coherence and eventually loss of functionality, highly analogous to cancer. Daddy Long Legs are essentially malignant tumors.
