A little more info on the sinistral shells would be helpful,
especially size and location. "Himalaya"? Really?
The gastropods are a mixed bag. The smooth ones with crystals
or agate inside (1,2,3,5 and 8) look like Physa, a common, fossil
and recent genus of left handed fresh water shells. They are possibly
too big to be in that genus. The two (shells 4 and 6) that look
like Busycon are probably Florida Pliocene fossils. The presence
of an other unrelated, Recent shell ( 7, which is not sinistral
anyway) implies a 'collection' from multiple sources, not all local.
In a link http://www.induskunst.dk/shells.html
, Shell No. 7 appears to be the species Volva volva Linn. (Family
: Cypraeidae), commonly known as 'Shuttle Shell'. This shell is
located at Andaman & Nicobar, Lakshadweep islands of India.
Its status is 'uncommon'.
With best wishes, Chandrashekhar P.
Sinistral fossil - probably Glyptophysa (if cainate) or Physa
sp Kumar Himalayas fossil - Buccinidae. Judging by labral sinus