Here is an interesting article on the BBC news website concerning the fossils of 'harvest men' as they are known, they look much like your average
long spindly legged spider.
Its seem that they have not changed much over the course of 300million years, apart from the fact that they look more alien back then.
www.bbc.co.uk...
Some scientists have used a special 3D x-ray too make a 3 dimensional video / animation of the said creatures
Please see links for full article (bbc.co.uk/news)