James:
When you posted the question, I asked Dr. E. Alison Kay, who specializes
in Cypraea if she has heard of cowries using acid as a defense.  She
hadn't heard of that, but said, "There have been reports in the
literature that acids have been detected in mantle cells of cowries. The
only example that comes to mind at the moment (without me going through
my literature lists) is that of some evidence for acid secretion in
Trivia. I can try to track the reports down, but not today! Alison
--
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