Scottish Rock Garden Club Forum

Plant Identification => Plant Identification Questions and Answers => Topic started by: Egon27 on November 09, 2015, 05:07:11 PM

Title: Interesting stone
Post by: Egon27 on November 09, 2015, 05:07:11 PM: I found in the garden of stone [flint] with small but distinct characters. Can anyone explain what this is? The characters are small, 3-4 mm in diameter.
Title: Re: Interesting stone
Post by: Carlo on November 09, 2015, 05:35:51 PM: I'd start nosing around in fossil resources. I've seen many, but nothing like this--and I'm no expert.
Title: Re: Interesting stone
Post by: Martinr on November 09, 2015, 05:50:50 PM: looks like an ancient equivalent of a sea urchin
Title: Re: Interesting stone
Post by: Graham Catlow on November 09, 2015, 06:55:29 PM: Try Googling Blastoids. Extinct Echinodermata. Related to the sea urchin as Martin suggests.
Title: Re: Interesting stone
Post by: James Cheshire on November 10, 2015, 01:36:39 AM: These are crinoid (sea lily) stem impressions. It's an echinoderm, related to sea urchins and starfish. More information here. (http://northislandexplorer.com/fossils/permiancrinoids.htm) Beautiful find!
Title: Re: Interesting stone
Post by: Mavers on November 10, 2015, 10:26:27 AM: Wow, how old would these fossils be?

they're beautiful Egon.
Title: Re: Interesting stone
Post by: David Nicholson on November 10, 2015, 10:46:52 AM: As far as I can find out these come from a period around 550 million years ago. It's all relative though, no point in singing Happy Birthday to 'em ;D
Title: Re: Interesting stone
Post by: Martinr on November 10, 2015, 10:57:27 AM: Don't think they're quite that old
Title: Re: Interesting stone
Post by: David Nicholson on November 10, 2015, 11:10:46 AM: Quote from: David Nicholson on November 10, 2015, 10:46:52 AM
............................. It's all relative though, no point in singing Happy Birthday to 'em ;D

;)
Title: Re: Interesting stone
Post by: Maggi Young on November 10, 2015, 11:33:46 AM: Quote from: James Cheshire on November 10, 2015, 01:36:39 AM
These are crinoid (sea lily) stem impressions. It's an echinoderm, related to sea urchins and starfish. More information here. (http://northislandexplorer.com/fossils/permiancrinoids.htm) Beautiful find!

Fascinating - and useful- information, James - thank you!!

And they're possibly "just" 252 million years old - quite something , isn't it?
Title: Re: Interesting stone
Post by: Egon27 on November 10, 2015, 02:09:16 PM: Thank you all. I have two question: Why elements of these creatures are raised? It should probably be concave if imprint in stone. Second problem: the selected portion of the picture is probably no living organism?
Title: Re: Interesting stone
Post by: Maggi Young on November 10, 2015, 02:12:20 PM: I presume the raised portions in the stone are made by the concave (hollow) portions of the original stems.
Title: Re: Interesting stone
Post by: James Cheshire on November 11, 2015, 05:07:03 PM: You are correct, Maggie. :)

A crinoid stem is composed of stacked coin-like segments, called columnals. The fossil circled in red is a portion of stem on its side. The other fossils are on-end. Originally the fossils were cylindrical pieces, but they dissolved away ages ago. Only the impressions remain (these are called external molds).

Here are pictures of a crinoid stem portion from Ohio. The central hole is called the lumen.

James
Title: Re: Interesting stone
Post by: Maggi Young on November 11, 2015, 05:34:59 PM: Fossils are quite riveting - well not always so for the human versions!! :-X
Title: Re: Interesting stone
Post by: Tristan_He on November 11, 2015, 08:09:26 PM: Beautiful fossils. Echinoderms really are a work of art.

@ James - out of interest, how do you tell crinoid stem from blastoid?

Tristan
Title: Re: Interesting stone
Post by: mark smyth on November 11, 2015, 10:32:36 PM: please post larger photos
Title: Re: Interesting stone
Post by: Maggi Young on November 12, 2015, 10:58:06 AM: Quote from: mark smyth on November 11, 2015, 10:32:36 PM
please post larger photos

The photos are very clear here just on opening - but they also enlarge well with scrolling, Mark.
Title: Re: Interesting stone
Post by: Tristan_He on November 12, 2015, 08:49:51 PM: Kind of appropriate that we are discussing crinoids since to my knowledge they are one of the few non-plant groups that possesses both a stalk and a calyx!

They are still around today of course, and the living organisms rival any flower in beauty

https://upload.wikimedia.org/wikipedia/commons/d/d2/Crinoid_on_the_reef_of_Batu_Moncho_Island.JPG (https://upload.wikimedia.org/wikipedia/commons/d/d2/Crinoid_on_the_reef_of_Batu_Moncho_Island.JPG)

https://upload.wikimedia.org/wikipedia/commons/4/42/Colorful_crinoids_at_shallow_waters_of_Gili_Lawa_Laut.JPG (https://upload.wikimedia.org/wikipedia/commons/4/42/Colorful_crinoids_at_shallow_waters_of_Gili_Lawa_Laut.JPG)

http://www.deepseanews.com/wp-content/uploads/2006/12/Neo-decorus-closeup.jpg (http://www.deepseanews.com/wp-content/uploads/2006/12/Neo-decorus-closeup.jpg)
Title: Re: Interesting stone
Post by: Maggi Young on November 12, 2015, 08:52:22 PM: My word - what colours! They can be bright can't they?
Title: Re: Interesting stone
Post by: James Cheshire on November 14, 2015, 07:54:03 PM: Quote
@ James - out of interest, how do you tell crinoid stem from blastoid?

There's no way to tell them apart from stems alone. Crinoids are much more abundant and widespread than blastoids in most rocks, so it's usually safe to assume that any stem remains belong to crinoids.
Title: Re: Interesting stone
Post by: Tristan_He on November 15, 2015, 02:43:50 PM: OK thanks. Looking on Wikipedia it looks like blastoids died out at the end of the Permian, so I guess rock age could help?