If you have ever been to a museum, then you definitely saw oval creatures on a stone the size of a matchbox. These are trilobites - a completely extinct group of arthropods, which in their appearance don't resemble any of the familiar animals. The amazing trilobites are popular collectibles due to their variety. Extraordinary trilobites are gone more than 200 million years ago, so today we can only admire their fossils. The Materials Trilobite Fossil cursor for a mouse!