Balls of moss move like a flock

Squishy pillows of moss appear to slowly move across glaciers in a coordinated fashion, researchers have found. In a long-term study in Alaska, researchers tagged the rolling ‘glacier mice’ to monitor their motion. The herd seems to move in unison, at a speed of about 2.5 centimetres per day. Their motion didn’t align with the prevailing winds, and they weren’t rolling down a slope — so what propels them is still a mystery.