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Rods, Cylinders, Tubes etc

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  • Rods, Cylinders, Tubes etc

    SEA URCHIN (ECHINOID) SPINES
    [compiled by painshill]

    Here’s a couple of items for which ID’s have been requested in the past:

    Click image for larger version

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    Picture posted by Morgan from Alabama on our Facebook page



    Pictures (edited) from member [TXRPLS]


    Both of these are sea-urchin (echinoid) spines – the first one is natural shell and the second one is fossilised (an internal cast of the original spine). These items are frequently mistaken as artefacts – either bone or stone, depending on whether they are fossilised or not. The examples above show no sign of modification.

    Sea urchins have a worldwide distribution and their detached spines are common beach finds – frequently being found in clusters or even in large quantities where they have been sorted by wave action. Fossilised spines are also relatively common in areas with sedimentary marine deposits. The term “spine” conjures up something sharp and pointed, which is the type most frequently depicted in books but many species have relatively blunt spines used as a means of locomotion rather than for defence. Like this:


    [pic by FJ Gahn on National Geographic website]


    These kinds or urchins are from the order “Cidaroida”, known as pencil urchins or sometimes slate-pencil urchins since the fat blunt spines resemble the shape of the pencils used in olden times with a slate board. They’re particularly common in waters of the central and southern regions of the Atlantic coast of America. In modern times they have commonly been bulk collected and drilled (either end-to-end or cross-wise at one end) for use in arts and crafts to make decorative items such as flys-creen curtains, wind-chimes, plant-hanging baskets, lamp-shades and jewellery. Here’s some examples:


    [pic from shells-of-aquarius website]


    Features to Look for

    In some urchins the spines may have a bulbous end, or a shape that resembles a bowling pin with a rounded bottom. One end normally has a cap-like feature (the articulation -and- attachment point to the shell or “test” of the urchin) with a small dimple that may have a hole if unfossilised. You can see those features on the first two pictures. They’re at least partially hollow if unfossilised, but the hole doesn’t go all the way through unless one end is broken. The cross-section may be approximately round or a rounded angular shape, which you can see in the second picture and on some specimens in the fourth picture.

    The colours are usually pinks, browns and creams but some species are bright red. There may be striations or ridges running longitudinally from end to end and unfossilised ones may have lateral bands of different colours (sometimes bright, but they also fade after detachment from the animal).

    Native Americans certainly used unfossilised ones for beads but usually one or both ends was sawn or snapped off to create a tube, or they were drilled laterally for suspension. There would need to be context to confirm such use.
    Last edited by painshill; 01-28-2016, 09:55 AM.
    Look to the ground for it holds the past!
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