Shadow Critter
From Threesong
Detritus of minds and souls that don't harden into a undead individuals can rot and grow into a part of a Shadowfell ecosystem which is very much a type of life. These "plants" and "animals" are "undead" for the purposes of interacting with positive and negative energy and spiritual powers such as Turn Undead, but they have solid bodies with vital organs and as such don't have many basic undead immunities. Most deal cold damage as they absorb energy, but they're not immune to cold.
