1. The Eiffel Tower can be 15 cm taller during the summer. When the temperature increases, the iron from which the tower is built expands, making the tower slightly taller. 2. Octopuses have blue blood. To adapt to cold, deep ocean environments, octopuses evolved a copper-based blood called hemocyanin, which is more efficient at transporting oxygen in low temperatures than hemoglobin. 3. Sharks existed before trees. Sharks date back to about 400 million years ago, while the first trees appeared around 350 million years ago, making sharks older than trees.