scientists have discovered the fossilised remains of a marine animal, perhaps a sponge or coral, which they say lived nearly 550 million years ago.

The creature's hard, shelly parts are far more complex than anything else found from this time. It gives researchers an insight into a period of Earth history just before life forms on our planet are thought to have gone through many rapid changes. "This was a crucial time in evolution in terms of the fossil record,' says Rachel Wood, from uk-based Schlumberger Cambridge Research, who made the discovery. "It's when multi-celled animals started to get hard skeletons. The recently discovered fossil has a much more complex biomineralised shell than we've seen before. It's also very big and can reach up to a metre.'

The researchers found the fossil in a reef in Namibia. The creature, which has been classified as Namapoikia reitogensis, comprises a series of tubules, each just a few millimetres in diameter. These hard parts are fully biomineralised