History of invertebrate paleozoology and simpler sea-dwelling organisms. By far, invertebrate paleozoology is the easiest type of fossil collecting. "Unlike" the difficult-to-analyze and hard-to-interpret fossils of paleobotany (plants) and micropaleontology (microbes), and "unlike" the rarely found and poorly preserved skeletons of vertebrate paleontology, invertebrate fossils are usually both common and simple to identify. This is because many prehistoric invertebrates were hard-shelled mollusks, brachiopods, trilobites, bryozoans, crinoids or corals who were buried amid marine, sediment-preserving conditions; and therefore frequently fossilized. Stone-age people were without doubt the very first fossil collectors. Fossilized echinoderms have been found in Dunstable, Bedfordshire, central England, decorating a long-buried human skeleton;
Physalia on beaches, where their toxic nematocysts can remain potent for weeks or months in moist conditions. Both species of this siphonophore resemble a jellyfish in appearance, with their gas-filled float and cluster of polyps beneath, which can hang up to 30 or 165 feet below the surface of the sea. The species "Physalia utriculus" is given the common name Pacific man o' war to distinguish it from the more widely distributed and larger "Physalia physalis", the Portuguese man o' war. The species are told apart by the size of the float (six inches compared to twelve) and by having a