Upper Bowland Shales,
Weets Hill, Barnoldswick
A local find!
This curious fossil is a Rostroconch. The Rostrochonchia are a group of Palaeozoic bivalved molluscs that in early times were considered Bivalves. Further research by palaeontologists' concluded that they warrant a distinct class of their own, the Rostrochonchia. The Rostrochonchia are divided into two orders:
(Early Cambrian to Early Silurian)
(Late Cambrian to Late Permian)
They probably lived a sedentary semi-infaunal lifestyle.
Whitby Mudstone Group, Lower Jurassic,
Runswick Bay, East Yorkshire
Sometimes sorting out fossils can be a problem. A good example is Pseudomytiloides dubius - originally described in the early 19th century I think, by J. Sowerby.
Mytiloides is the modern mussel so I guess the original description thought it was dubiously like the mussel, hence Mytiloides dubius.
Later redescription assigned it to Inoceramus, then it got its own genus Pseudomytiloides.