Allonautilus scrobiculatus

The nautilus is a pelagic marine mollusc of the cephalopod family Nautilidae. The nautilus is the sole extant family of the superfamily Nautilaceae and of its smaller but near equal suborder, Nautilina.

New Guinea is the world's second-largest island, with an area of 785,753 km2 (303,381 sq mi). Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the 150-kilometre wide Torres Strait, though both landmasses lie on the same continental shelf. Numerous smaller islands are located to the west and east.

New Britain is the largest island in the Bismarck Archipelago, part of the Islands Region of Papua New Guinea. It is separated from New Guinea by a northwest corner of the Solomon Sea and from New Ireland by St. George's Channel. The main towns of New Britain are Rabaul/Kokopo and Kimbe. The island is roughly the size of Taiwan. While the island was part of German New Guinea, it was named Neupommern . In common with most of the Bismarcks it was largely formed by volcanic processes, and has active volcanoes including Ulawun, Langila, the Garbuna Group, the Sulu Range, and the volcanoes Tavurvur and Vulcan of the Rabaul caldera. A major eruption of Tavurvur in 1994 destroyed the East New Britain provincial capital of Rabaul. Most of the town still lies under metres of ash, and the capital has been moved to nearby Kokopo.

Milne Bay is a large bay in Milne Bay Province, south-eastern Papua New Guinea. More than 35 kilometres long and over 15 kilometres wide, Milne Bay is a sheltered deep-water harbor accessible via Ward Hunt Strait. It is surrounded by the heavily wooded Stirling Range to the north and south, and on the northern shore, a narrow coastal strip, soggy with sago and mangrove swamps. The bay is named after Sir Alexander Milne.

Solomon Islands is an island country consisting of six major islands and over 900 smaller islands in Oceania, to the east of Papua New Guinea and northwest of Vanuatu. It has a land area of 28,400 square kilometres (11,000 sq mi), and a population of approximately 700,000. Its capital, Honiara, is located on the largest island, Guadalcanal. The country takes its name from the wider area of the Solomon Islands (archipelago), which is a collection of Melanesian islands that also includes the Autonomous Region of Bougainville, but excludes the Santa Cruz Islands.

The umbilicus of a shell is the axially aligned, hollow cone-shaped space within the whorls of a coiled mollusc shell. The term umbilicus is often used in descriptions of gastropod shells, i.e. it is a feature present on the ventral side of many snail shells, including some species of sea snails, land snails, and freshwater snails.

Allonautilus perforatus also known as the Bali chambered nautilus, is a species of nautilus native to the waters around Bali, Indonesia. It is known only from drifted shells and, as such, is the least studied of the six recognized nautilus species. Thus, not much is known about it outside of the shell.

Nautilus is a genus of cephalopods in the family Nautilidae. Species in this genus differ significantly in terms of morphology from those placed in the sister taxon Allonautilus. The oldest fossils of the genus are known from the Late Eocene Hoko River Formation, in Washington State and from Late-Eocene to Early Oligocene sediments in Kazakhstan. The oldest fossils of the modern species Nautilus pompilius are from Early Pleistocene sediments off the coast of Luzon in the Philippines.

The periostracum is a thin, organic coating that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods and bivalves, but it is also found in cephalopods such as Allonautilus scrobiculatus. The periostracum is an integral part of the shell, and it forms as the shell forms, along with the other shell layers. The periostracum is used to protect the organism from corrosion.

A gill is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are kept moist. The microscopic structure of a gill presents a large surface area to the external environment. Branchia is the zoologists' name for gills.