I am a newbie to shell collecting.  Living thousands of kilometers from
any ocean makes it hard to be seriously active in the science, but I
have managed to beg, scrounge, trade, buy and even collect a few shells
over the years.  About 10 years ago I was lucky to be on a geological
field trip on the coast of South Carolina and I collected a number of
beach shells.  I found a shell that look exactly like the Lightning
Whelk, light brown, and a couple of inches long (according to the
pictures in the various books I have used), except that mine is dextral,
not sinistral, as the Lightning Whelk is supposed to be.  What do I
likely have?  I had several at the time, but gave them all away but
one.  I can't remember if they were all dextral or not.  I didn't know
enough to think about it at the time.
While we are on the topic, why is it that most shells are dextrally
whorled, and how common are sinistral variations?  Are some species more
prone to this than others?
By the way, I have learned a lot just by keeping up with this group.
You are all obviously passionate about your hobby, and there is a huge
wealth of knowledge out there.  I don't feel quite so far from the ocean
now...