>What is making the holes, nay, tunnels in the shells of panamic cones I
>found in San Carlos? There appears to be something still in the holes,
>something that looks like a small bivalve or gooseneck barnacle. Are
>these shipworms? I haven't seen anything like this in shells from the
>Bahamas or Hawaii.

If there is just a plain opening in the shell surface and you can see
a couple of valves within (valves which when closed do not gape ie
the margins are straight) it's a mytilid eg Lithophaga.

If there is a tube built onto the opening (possibly broken off) and
signs that the inside of the bored shell has a swelling there, it's a
gastrochaenid (eg Gastrochaena), which produces a calcareous crypt to
live in.

Both groups occur worldwide in warm 9and not-so-warm!) seas. Neither
are related to shipworms (Teredinidae and Xylophagidae), which only
bore into wood or soft sediments. Teredinids secrete calcitic tubes
to line their burrows; xylophagids, which closely resemble them, do
not.
--
Andrew Grebneff
165 Evans St, Dunedin, New Zealand
64 (3) 473-8863
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Fossil preparator
Seashell, Macintosh & VW/Toyota van nut
I want your sinistral gastropods!