Actually, I have another suggestion. If those are mainly feeding trace grooves rather than tentacles (the photo size is too small to tell, and there is high contrast, but I am suspicious) it could be an echiuran burrow in the middle. They have amazingly long reach with a single proboscis. Yes, terebellids get very big - but don't they have many more tentacles than that?
Geoff
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Geoff Read <g.read from niwa.co.nz>
http://www.annelida.net/http://www.niwa.co.nz/about-niwa
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>>> On 22/04/2010 at 2:43 a.m., ericthenybui <erics from hi.is> wrote:
> I am a researcher working in Iceland. I analyze photographs and video of the
> sea floor to identify organisms and draw conclusions about community
> structure which are then related to environmental factors. I found recently
> an organism on one of the slides that I am not sure how to identify. It is
> clearly an infaunal organism with tentacles that radiate out from a central
> point. The problem is the size. Judging by the fact that the image is about
> 0.6 sq. m, the tentacles are more than 30 cm long...which would mean that
> the animal is also at least that long. This seems too long to be a
> terebellid to me, but I don't know any other taxa that has many long smooth
> tentacles that are dragged across the sediment. So, I ask you folks...how
> big do terebellids get? Here's the picture:
>http://www.flickr.com/photos/ericdossantos/4540826876/
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