Otters have pockets under their arms for carrying their favourite snacks and rocks.

True—especially for sea otters. They have loose skin folds under their forearms that work like “pockets,” where they stash collected prey (like clams, crabs, and sea urchins) and often a favorite rock. Floating on their backs, they use that rock as a tool to crack tough shells on their chest—one of the few examples of regular tool use in mammals. These pockets let sea otters gather multiple items in one dive, conserve energy in cold Pacific waters, and eat safely at the surface. Memory tip: think “hoodie sleeves”—sea otters keep snacks and a pocket rock tucked under their arms, ready for mealtime.