"Grungs are small, colorful, and very territorial. As they age, their skin changes colors, with red being youngest and golden being oldest. One must exercise extreme caution when interacting with them, as a simple touch of their skin releases their toxins, which can range from painful to deadly. Native only to Adraria's hot and humid rainforests, they pose little threat to overall geopolitical stability. That being said, their territorial boundaries are distinctly marked by their primitive symbols left on trees, and don't tend to extend over large swaths of land. Thus, conflicts between Grungs and native Adrarians are very rare."
-Excerpt from Volo's Guide to Ozelan Beasts