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Fossil sea urchin

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Description

Photographed with dealer's permission at the 2011 Hobart Gem and Mineral Fair, Tasmania, Australia. The top of the image has been cropped to omit a 'Do Not Touch' sign. This >20cm wide slab is extremely fragile.

Archaeocidaris brownwoodensis
Age: Late Carboniferous (Missourian), Canyon Group, Winchell Formation
Locality: Lake Brownwood Spillway, 14km north of Brownwood, Brown County, Texas, USA

Sea urchins, also known as echinoids, evolved in the Ordovician Period (450 million years ago) and have since diversified into many lineages, not all of which have survived to this day. Order Cidaroida, to which Archaeocidaris brownwoodensis belonged, is now extinct.

It was first described in 2005. [link]

The spines of dead sea urchins detach easily, making articulated specimens like this one rarer and more valuable.

Sea urchins and their relatives, the sea dollars, make up the class Echinoidea. They are slow moving, globular, spiny animals about 3-10cm across that feed on algae and are in turn preyed on by fish and humans. Interestingly, although adult sea urchins have five-fold radial symmetry (similar to a starfish), early larvae have bilateral symmetry (similar to fish, mammals, etc).

On sea urchins: [link]

Yes! This image is FREE for non-commercial use as stock, reference or manipulation. Please Note me for commercial or other use.
Image size
1082x713px 354.33 KB
Make
Canon
Model
Canon PowerShot A480
Shutter Speed
1/30 second
Aperture
F/3.0
Focal Length
7 mm
ISO Speed
400
Sensor Size
6mm
© 2011 - 2024 greenzaku
Comments9
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KutkuMegsan's avatar
Amazing specimen ^_^