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;
Portuguese man o' war polyps are attached to one another and physiologically integrated, to the extent that they cannot survive independently, creating a symbiotic relationship, requiring each polyp to work together and function like an individual animal. The Indo-Pacific Portuguese man-of-war ("P. utriculus"), or blue bottle, is a related species with very similar appearance found throughout the Indian and Pacific Oceans. The name "man o' war" comes from the man-of-war, an 18th-century armed sailing ship, and the cnidarian's resemblance to the Portuguese version at full sail. The Atlantic Portuguese man o' war lives at the surface of the ocean. The gas-filled bladder, or pneumatophore,