Nautilus shell cut in half. The chambers are clearly visible and arranged in a logarithmic spiral. The nautilus shell is composed of 2 layers: a matte white outer layer, and a striking white iridescent inner layer. The innermost portion of the shell is a pearlescent blue-gray. The osmena pearl, contrarily to its name, is not a pearl, but a jewellery product derived from this part of the shell. Caption and Photo source: ©© Chris 73 / Wikimedia Commons
Excerpts; The New york Times
It is a living fossil whose ancestors go back a half billion years, to the early days of complex life on the planet, when the land was barren and the seas were warm.
The word “nautilus” comes from the Greek for boat. When the first shells arrived in Renaissance Europe, collectors were stunned: They saw the perfect spirals as reflecting the larger order of the universe.
Nautilus lives on the slopes of deep coral reefs in the warm southwestern Pacific, but scientists say, humans are loving the chambered nautilus to death, throwing its very existence into danger…
Palau nautilus in cage after being captured, from a depth of approximately 30m. Palau, Micronesia. Caption and Photo source: ©© Lee R. Berger / Wikimedia Commons