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 much as above the water. The Portuguese man o' war fills its gas bladder with up to 14% carbon monoxide. The remainder is nitrogen, oxygen, and argon—atmospheric gases that diffuse into the gas bladder. Carbon dioxide also occurs at trace levels. The sail is equipped with a siphon. In the event of a surface attack, the sail can be deflated, allowing the colony to temporarily submerge. The other three polyp types are known as dactylozooid (defense), gonozooid (reproduction), and gastrozooid (feeding). These polyps are clustered. The dactylozooids make up the tentacles that are typically in length, but can reach over