While exploring the swamplands of Crius you might stumble across the tracks of a grumblewamp. This rarely seen creature spends the majority of its time burrowing beneath the mud seeking out tasty insects with their superb sense of smell. However, swamp locals know how to spot a grumblewamps trail. These trails look like someone drew an unbroken line across the mud's surface in a wavy pattern. This particular trail is due to the row of spines along the Grumblewamps’ back. The spines help them deter potential predators but at the same time often draw a line in the mud, above them when they get close enough to the surface. Despite spending the majority of their time beneath the surface, Grumblewamps do occasionally take to the water. Their streamline bodies and finned tail make them agile swimmers. This constant exposure to either mud or water leads their fur to become the perfect breeding ground for aquatic algae and moss. The moss that grows from them is known by locals as Wampmoss and is a sought after alchemical ingredient. Sadly, this has led to an uptick in poaching for the poor Grumblewamps. Now sightings of Grumblewamps have steadily declined but most swamp dwellers still believe there are Grumblewamps hiding beneath the mud and mire of the swamp. 

Credit to Turtleynuts, Red1al, DerRest, and Silviesanguine for some lore ideas.