Dear Ross;-
    This reply comes from a disaster movie. What happened was the
Earth used to spin in the other direction. Then this here meteor
crashed in either in Mexico or New Jersey and destroyed the dinesaurs
and Lawrence Welk. The meteor came in at a 45 degree angle which
stopped the existing spin and sent it  in the other direction. At
that time, righthanded shells were called "sinistral" and brought
especially high prices. The busycon whelks were all buried at the
time, and never noticed the change. I do hope our science is thus
enriched.
    Art