This is a really cool and rare heteromorph ammonite (Nostoceras hetonaiense) fossil from the Mukawa-cho, Hokkaido. Unlike most ammonites that are tightly coiled, spiral shell that retains it's shape throughout it's life, heteromorph ammonites have irregularly-coiled or uncoiled shells. These hetermorph ammonites are Late Campanian–early Maastrichtian. The specimen is preparaed 3D, much of the surrounding limestone has been painstakingly removed. Specimen preserves part of the original conch, white color. Tubercles are still preserved and visible on the juvenile part. A calcite vein cross the matrix and the specimen. Another partial specimen is present on matrix. This specimen is 100% natural, not restored. As many heteromorph specimens from that site during preparation some part are glued. Ammonite is 9 cm Overall size 13 x 10 cm. Nostoceras hetonaiense Mukawa-cho, Hokkaido, Japan. Late Cretaceous in age (Late Campanian Stage)