They very much resemble tubes formed by Sabellaridae (Polychaeta). I understand that Phragmatopoma forms considerable reefs in American waters.
Regards,
Barrie Jamieson
Barrie Jamieson B.Sc., Ph.D., D.Sc.
Emeritus Professor
Department of Zology and Entomology
School of Integrative Biology
University of Queeensland
Brisbane
Queensland 4072
Australia
-----Original Message-----
From: annelida-bounces from oat.bio.indiana.edu on behalf of Spinnaker
Sent: Tue 12/29/2009 1:42 AM
To: annelida from magpie.bio.indiana.edu
Subject: [Annelida] Mystery worm rock
Hello,
I'm hoping for some help with a mystery rock found on a southern North
Carolina (USA) beach fronting the Atlantic Ocean (image attached).
A preliminary guess is that they are Serpulid colonies, but the form seems a
little strange for that.
The rocks are occasionally found washed ashore on the sandy beach. They have
been surf-worn, and are in rounded, flattened masses 5-30 cm in greatest
diameter. Their varied colors (black, gray, orange-brown, light tan suggest
that they have been buried in differing sediments.
Close examination reveals that the rocks are highly porous and composed of a
mass of tubes. The tubes appear calcareous, with no constituent sand grains
visible through a loupe. The tubes are eroded open on the rock's exterior,
and are circular, oval, or indented-oval in cross section, 1-3 mm in
diameter.
I have numerous higher resolution images if needed.
Many thanks for any help with this puzzle.
Cheers,
Blair Witherington
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