Glaciers(冰川) are large bodies of ice and snow. Because they're so icy, it's very hard for things to live on them. But glacier mice do somehow.
Of course, glacier mice aren't mice. They're round balls of moss(苔藓) that can grow to about the size of a tennis ball. They're usually found in groups near small rocks on the surface of icy glaciers.
Normal moss can't form on a glacier, so scientists believe glacier mice probably form around something small, like a bit of dust(尘土). Because staying on the ice too long would kill the moss, glacier mice form into a ball. It allows them to move around, so that their different parts touch the ice at different times.
Some scientists once did an experiment on glacier mice. They put a small device( 装 置 ) inside 30 glacier mice to follow their movements. They learned that the mice traveled about 2.5 centimeters(厘米) a day. They seemed to move in groups. They moved in the same direction and at about the same speed, almost like a group of animals. The scientists tested several ideas that might explain how the mice moved together, such as rolling downhill, being blown by the wind, or following the sun. None of these could explain the movement of the glacier mice.
Glacier mice are still a mystery to scientists. For their next experiment, the scientists said they would use cameras to take pictures of the movements of the mice over a long period of time. Are you looking forward to getting the answer?
