Opalized ammonite fossils are some of the most unique and spectacular paleontological specimens. They were formed through a ...

Some species would begin growing their shell in a tight spiral but straighten it out through later growth phases. There were also some more unusual shapes - the species Nipponites mirabilis, which is ...

Based on the fossil record, ammonites came in a wide range of sizes and shapes, from smaller than an inch to as large as nine feet wide. Some ammonites had long, straight shells, while others had ...