Labels:text | animal | invertebrate OCR: 450 MYA NAUTILOID MOLLUSK UNCOILED O NLY ONE TYPE of nautiloid FINAL SECTION survives today, although they were abundant in the Paleozoic Era. Nautiloids are a group of primitive sea-dwelling mollusks (soft-bodied animals without a backbone, protected by a hard shell). A nautiloid would have grasped its food with the tentacles that protruded from its shell. COILED SHELL SPIRAL SHELL This is the fossilized shell of a rare species of nautiloid.