>The fact that the inside of the shell is shiny is pretty good evidence
>that it is not  a polychaete but probably a gastropod.  It also looks
>like it has at least two distinct layers at the broken end, typical of
>gastropods.  The attached sand grains are odd, but not all that
>important.  Perhaps it is a vermetid protoconch (plus 1/2 whorl), which
>attaches itself to a substrate (generally larger than sand grains
>though...)

I have seen polychaet tubes which are quite glossy within. I have
seen vitreous epitoniiform ones as well, translucent... really
beautiful. Generally I think calcaeous polychaet tubes don't have
sediment grains attached. However some tubes are composed of
sandgrains glued with mucus or parchmentlike proteins (eg sabellids).

>Thanks, Allen. My first impression was that this is some sort of
>vermetid although I confess I'm still fooled by non-molluscan
>"worm-shells".
>
>Could the sand grain attachment be a behavior limited to an early
>phase of development? Could the behavior be limited to only a
>limited taxon within vermetidae?
>
>Agglutinated attachment seem to be a general behavior of
>Xenophoridae and Scaliolidae. Of course, the animal may "intend" to
>camouflage itself, but I think these external extras bring attention
>from hominid collectors and observers.

Penicillids also often have sediment grains attached to the crypt and
siphonal tube, and clavagellids incorporate larger fragments
occasionally, but of course neither of these groups of these tubular
bivalve are coiled. Well, the valves are, but they don't have grains
attached.

If you have an image I'd be happy to look at it; others might as well?
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
Seashell, Macintosh, VW/Toyota van nut
‚ Opinions stated are mine, not of the University of Otago
"There is water at the bottom of the ocean"  - Talking Heads

----------------------------------------------------------------------
[log in to unmask] - a forum for informal discussions on molluscs
To leave this list, click on the following web link:
http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1
Type your email address and name in the appropriate box and
click leave the list.
----------------------------------------------------------------------