Eurasian beaver
Eurasian beavers are one of the largest living species of rodents and are the largest rodent native to Eurasia. They weigh around . In Norway, adult males average while females average , while another study found adults from the same country to average . By the average weights known, the Eurasian beaver appears to be the world's second heaviest rodent behind the capybara, but averaging slightly larger and heavier than the North American beaver. While the largest specimen confirmed on record weighed , the Smithsonian has reported that this species can exceptionally exceed . Typically, the head-and-body length is and the tail length is .
Traditions and student activities at MIT
"Brass Rat" refers to the MIT class ring, which prominently features the school mascot beaver on the top surface. The ring is traditionally made of gold, the beaver is the largest North American rodent, hence "gold beaver" has informally become "Brass Rat" in student lingo.