EONS: A590 SUPERB SLICED & POLISHED AMMONITE, 7" -- 1¢
- Source: eBay
EONS: A590 SUPERB SLICED & POLISHED AMMONITE, 7" -- 1¢ OPEN
DESCRIPTION: This auction is for BOTH halves. This specimen was chipped out of the entombing rock, the fossilized barnacles removed, the outside then laboriously buffed, then it was sliced in half and polished by hand to a glossy finish. This gives us an inside look at the individual growth chambers and the story behind them: as the animal grew, it would extend the open end of the shell by adding a larger growth chamber, pull its body forward into the new chamber, and then seal the old one -- but not before evacuating the water from its old chamber. Thus, each time the shell got bigger by one chamber, the newly sealed chamber maintained neutral buoyancy. Unlike a fish, the ammonite had neither lateral fins nor an air bladder, so it needed the air-filled chambers to keep it from sinking to the bottom.
Eventually though, when the animal died, it did sink to the bottom w it was covered by sediment which became rock after eons of high pressure and heat which occur miles below the Earth's surface. During that process, the individual chambers experienced different fates. The chambers that ruptured relatively immediately became filled with gray organic-rich sediment, which are time capsules of the ocean bottom at that time. Microscopic analysis shows tiny... read more