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Although they look like flowers, Crinoids are and were animals; However, when you look at them closely, you can see why they are sometimes called 'sea lilies.'
Crinoids are actually primitive echinoderms, and so are related to
Fossil crinoids date back almost 500 million years to the Cambrian Period. And through the rest of the Palaeozoic Era, they were very abundant, sometimes living in large accumulations known as 'crinoid gardens.'
Taking A Closer Look
Crinoids resembled long-stemmed flowers, with a central 'cup' containing the soft parts of the animal, numerous branching 'arms' and a stem up to 30 meters long which attached the animal to the ocean floor.
Here's what they looked like:
 
When the animals died, the ocean currents often broke up the remains and rolled them together in vast amounts to form thick deposits of limestone.
Because they were so numerous, Crinoid fossils are found around the world.
Most modern crinoids have more flexible arms than the fossil species and do not have stalks (at least as adults), but are free to swim or crawl over the sea floor. These types of crinoids are sometimes called 'feather stars.'
Words To Learn
Echinoderms http://en.wikipedia.org/wiki/Echinoderms
- Cambrian Period About 545 to 490 million years ago
The first fossils of animals with shells or hard parts occur in rocks of Cambrian age. Life in the Cambrian was confined to the sea and included the first representatives of many invertebrate animals.
The first vertebrate animals are known from late in this period. The Cambrian is sometimes called the 'Age of Trilobites', as these were one of the most dominant life forms.
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