There's one tiny fragment of DNA that pretty much all vertebrates and invertebrates share. It's the only piece of DNA known to be a billion years old — and it still has a role to play in shaping our genes.
Masonry is serious business for mason bees. They build their brood cells inside cavities such as hollow reeds, rotting wood or cracks in buildings. They first fill these cells with pollen and nectar, to feed the larvae that will grow inside, before sealing them off with a mix of mud and sand.
Just below the surface of the sea, little animals are floating through a universe where the stars are made of plankton. They travel in what can best be described as gelatinous spaceships, which provide both shelter and food. They are Oikopleura dioica (Oikos is ancient Greek for house or household).