The veil between the world of the living and the dead is quite blurry in the swamps, making it tricky sometimes for souls to pass onto the next plane peacefully. So an unfortunate soul who perishes in this swamp may rise again reborn as an Aggregate. This is not the destiny of everyone who dies in these swamps, but when a lost soul unable to cross over panics and attempts to reform with themselves horrid things can occur. If lucky their body will merge with the foliage of the swamp and become a Swamp Walker. But if their body is too badly damaged the soul has to grab whatever parts are available to make a new body. This does make their overall appearance change drastically from specimen to specimen as it depends on what were the nearest parts available when it was formed. Once created the soul has a difficult time discerning what it was while alive. Generally not hostile towards humanoids, but they can become quite a pest as they will steal pets or livestock. It’s believed they do this in an attempt to harvest the parts to help make themselves whole again.