Sentence Completion

Complete the sentence with ONE word from the passage for each blank.

The tardigrade, often called the water bear, is a microscopic animal famed for its toughness. When conditions become harsh, it can curl into a dried-out state known as a tun, slowing its metabolism almost to a halt. In this form it has survived boiling temperatures, freezing cold, intense radiation, and even the vacuum of space. Once water returns, the creature swells back to life within hours.

Under harsh conditions, the tardigrade dries into a state called a , and it returns to life once becomes available again.