Arthropleura were first mentioned in Neverseen, when they were called by Councillor Clarette. These herbivorous bugs are similar in appearance to boulders, and despite their plant diet, they are far from defenseless. Not only do they stretch a massive eight feet once they uncurl from their boulder-like form, but they also have a long forked antenna covered in slimey poison. It was mentioned by Sophie that these giant arthropods were supposedly extinct. Later in the novel, Fitz is impaled by an arthropleura, causing a life-threatening wound, which took Physic over a week to heal. He needed to throw up the poison, and it was named "The Great Vacker Hurlfest" by Keefe. This is also when Keefe finds out about Fitz's stuffed dragon, Mr. Snuggles.