Army of Sea Urchins? | Planet Earth | BBC Earth

Sea urchins gather in large enough numbers to form an army. Subscribe: WATCH MORE: New on Earth: Oceanscapes: Wild Thailand: “ Welcome to BBC EARTH! The world is an amazing place full of stories, beauty and natural wonder. Here you’ll find 50 years worth of astounding, entertaining, thought-provoking and educational natural history content. Dramatic, rare, and exclusive, nature doesn’t get more exciting than this. This is a commercial channel from BBC Studios. Service & Feedback