Anything, from anywhere, any age (Ordovician-Recent). Sinistrals,
turbinellids & epitoniids (best: sinistral epitoniids!) especially.

Best possible condition preferred, but anything is better than
nothing... I have lots of specimens represented only by small
fragments, but many of these are the only known specimen of
undescribed species, so it would be insane not to keep them. mine ios
a working scientific collection, so esthetics are not really
important. Those who collect only really nice specimens are missing
out on a lot...