Trumpet Worm tube, Serpulid Worm tube, Sand Mason Worm tube

Some marine worms build tubes around themselves, keeping them safe while they filter food from the sea. Trumpet Worms (left) mix a specially secreted glue with sand and shell fragments. Tube Worms (centre) build their armour by secreting calcium which hardens. Sand Mason Worms (right) make their tubes with mucus, sand, and shells.