Hello, CONCH-Lers!

I have an interesting shell about which to inquire -
Balcis martini A. Adams, 1854 (not sure if the author's
name should bein parentheses).

First of all, one of my books says these are parasitic; my
question is parasitic on what animal?

The other thing is that I am supposed to be pricing these
for our club's shell sell at a local festival, and I do
not have Rice's prices at hand.  The two specimens are 36
mm. and about 30 mm., and they are gem; but the data is
minimal.

I did find the species on a past auction with a starting
price of 2 euros.

Thanks,
Linda