Chambered nautilus

💡 Everyday Comparisons for Size, Mass & Speed

• 💡 Its shells are traded on a large scale; most are shells washed ashore on beaches, and the outer layer is sometimes stripped away to expose the silvery nacre (Australian Museum).
• 💡 It is commonly kept in public aquariums and has been bred successfully in captivity (Australian Museum).
• 💡 Its diameter of 22.2 cm is slightly larger than the short side of an A4 sheet of paper (21 cm), and its weight of 1.7 kg is slightly heavier than a 1.5 L bottle of water (about 1.5 kg) (Comparison).

Reference standards: coach bus ~12 m, mid-size car ~4.9 m, compact car ~1 t, basketball hoop 3.05 m, credit card 8.56 cm.