Filth crocs stay within their dank marshes, emerging only if prey wanders too close to their lairs. Sages speculate that these creatures are the result of necromantic experimentation by an ancient sahuagin lich named Klek-tiim. The extensive marshes were the only buffer zone between Klek-tiim's burgeoning kingdom and the mainland civilization. The lich wanted to stock the marshy borderland with creatures that would deter those who wished to destroy it. As one of the most numerable types of creatures in the marsh, the crocs became the target of undead transformation. Now, centuries later, the filth crocs continue to somehow maintain their numbers despite being slain at every opportunity.