From Overview:
Establishing a settlement in or near swamplands is a difficult task at best. Settlers have to contend with disease, vermin, flooding, predators, and a host of other conditions. While many of these can be overcome through perseverance, some obstacles are insurmountable. Grizimilaks are one such case. More than one settlement has been abandoned because of these well-meaning nuisances, often spreading the problem to other regions.
Grizimilaks are overly friendly swamp dwellers that believe they are of gnomish descent (a claim refuted by any sane gnome). Their short, almost goblinoid appearance, gnomish affinity, and constant trails of grime have earned this prolific race many derogatory names. They may be called sludge imps, grimekin, or hundreds of other names. They are most commonly called gnomblin, to the chagrin of both gnomes and goblins. Of course, high-spirited grizimilaks are oblivious to the insult.
Grizimilaks breed at an alarming rate, and have a surprisingly long lifespan. A single grizimilak, whether offering assistance or devising pranks, is a nuisance. In large numbers, the race reaches the levels of natural disaster. The race is very hardy, making an infestation nearly impossible to get rid of. Once a grizimilak adopts a person or a settlement, the end quickly follows.