article_snippet.sent: Fossils of Jurassic crinoids collected in Israel are pictured .
article_snippet.sent: Some 600 species of Crinoids are now extinct but the creatures live on in different forms in modern seas.
article_snippet.sent: Some 600 species of Crinoids have five  arms to snatch passing prey and a hidden mouth on the top.
article_snippet.sent: There are hundreds of species of extinct Crinoids, although the marine animal continues to live in seas today.
article_snippet.sent: The first Crinoids have a mouth on the top surface - next to The first Crinoids gut and anus - that's surrounded by feeding arms to grab passing prey.
article_snippet.sent: The first Crinoids generally have five main arms and a stem to attach The first Crinoids to rocks or the seabed.
article_snippet.sent: It's thought they were more common in ancient times, because limestone beds dating to the mid Palaeozoic are full of Crinoid fossils.
article_snippet.sent: The first Crinoids are thought to have appeared in the Ordovician period, between 488 million years ago and ending 444 million years ago and underwent a selective mass extinction at the end of the Permian period, where they evolved more flexible arms.
article_snippet.sent: Crinoid fossils look slightly different to reflect the variations across the species.
article_snippet.sent: Some 600 species of Crinoids are now extinct but the creatures live on in new forms in our seas today.
article_snippet.sent: This image shows a modern Crinoid, known as a Variable bushy feather star in the Philippines .