An article published today shows a paper that discusses a newly found fossil that would have looked something like this reconstruction when alive.
Aegirocassis benmoulae had modified legs, filters for feeding, and gills. These traits provide evidence for early arthropod evolution. This fossil has been dated to be over 480 million years old, and was found in Morocco. It's interesting how many new 'game changing' fossils are being found and how each of them adds something new to understanding evolution.