Sweetwater Crab in "Cave House" a143330875b191b81aec3c67e8c59756 such as quartz) during a

such as quartz) during a process called per-mineralization

meaning it does not form crystals

Its color and opacity are determined by the type of tree that produced the resin

This hunter / scavenger was literally a walking tripod

Sweetwater Crab in "Cave House" a143330875b191b81aec3c67e8c59756 such as quartz) during aCrabs nearest living relatives are scorpions, ticks, and land spiders. They are considered to be living fossils because of the great similarity between modern and fossil forms. Ranging from the Late Ordovician (roughly 450 million years ago) to the present, they are little changed in the last 250 million years.