During this stay I did some installation (Loughborough), workshops (Southampton, at NPL in Teddington , Leicester, ...) and I have also been to the Natural History Museum in London where I have held a quite old fossile in my hand.
It's Sphaerexochus britannicus, from the Silurian, Wenlock epoch. That
makes it between 423 and 428 million years old. Additionally, it is the "holotype", which means that the species S. britannicus is defined by this one physical specimen. The NHM has many of these type specimens, which is part of the reason our collections are so valuable to researchers.