Please identify the fossil in the picture below. size of pebble is around 40mm diameter and the pebble had been broken to reveal the internal structure.
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$\begingroup$ please add more details,a better location what types of rock can be found in the area.measurment of the fossils.it looks like some type of coral maybe take it to a museum for identification. $\endgroup$– trond hansenCommented Jul 17, 2019 at 5:38
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1$\begingroup$ Note to close votes most mineral identification criteria will not help identify a fossil. (although a scale would be helpful) $\endgroup$– JohnCommented Jul 17, 2019 at 16:23
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$\begingroup$ @gerrit You migth want to follow the advice of the paleontologist and do not point to the guide in the case of fossils. The question has 4 reopen votes. $\endgroup$– user12525Commented Jul 18, 2019 at 20:26
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1$\begingroup$ @Universal_learner Thank you. $\endgroup$– gerrit ♦Commented Jul 18, 2019 at 21:59
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$\begingroup$ @John My apologies. $\endgroup$– gerrit ♦Commented Jul 18, 2019 at 21:59
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2 Answers
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It a sea urchin fragment, or at least a natural mold of them. They have both the rings and the angliar joints. It is not uncommon for them to break up into clusters of those plates.
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These are fossilised crinoid discs. Crinoids are also known as sea lilies because of their plant-like appearance, but in fact they are animals related to starfish and sea urchins. There were many species, some modern representatives of which are still alive today. They had a long stem composed of stacked discs and topped by a flower-like bunch of feathery tentacles which filtered particles of food from the passing currents. The stem was anchored at the base to rocks on the sea floor. When they died, the stem tended to disintegrate into separate discs, and your specimen shows three or possibly four of them. They probably date from the Cretaceous. Chert, also known as flint, is a deposit of silicon dioxide which forms nodules in chalk sediments as they solidify.
answered Jul 17, 2019 at 6:58
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1$\begingroup$ It probably not a crinoid, the fact they are jointed makes a sea urchin fragment more likely. jurassiccoast.org/what-is-the-jurassic-coast/all-about-fossils/… $\endgroup$– JohnCommented Jul 17, 2019 at 16:30