The animal that can sleep for three years is the tardigrade, also known as the water bear. These microscopic creatures are renowned for their resilience, capable of surviving extreme conditions—including extreme temperatures, radiation, and even the vacuum of space. When faced with unfavorable conditions, tardigrades can enter a cryptobiotic state, effectively suspending their metabolism and allowing them to endure for years without water or food. This remarkable ability to adapt and survive has fascinated scientists and contributes to ongoing research into the potential for life in extreme environments beyond Earth, as well as practical implications for biology and medicine.