Hello Thomas,

Your new shell is not a mollusk, but a brachiopod, or "lamp shell",
perhaps in the genus Terebratulina, but I am not sure of the species.
There is little readily available literature on these animals, at least
as far as identification guides are concerned.

The other shells on your unidentified page appear to be:

#1 Yoldia hyperborea Loven
#2 Macoma calcarea (Gmelin)
Chlamys islandica (Muller) (all Pectinidae pictured appear to be this species)
Astarte borealis Schumacher (the bottom picture)

Regards,
Paul M.