Unemployed Philosophers Guild. The mug shows a prehistoric landscape populated by fierce dinosaurs. When you pour in a hot beverage, the eons pass before your eyes as the dinosaurs transform into fossils in a museum exhibition. • 14 oz. Ceramic coffee cup with a comfortable handle. • All of our disappearing mugs come in a beautifully designed, colorful box. • Heat activated color changing mugs are microwave safe, but not dishwasher safe. Hand wash only. Don't soak. • UPG is a novelty gift company specializing in smart and funny gifts. Check out our shop for all types of quirky fun stuff!