What is "nipponites"

Nipponites ("stone of Nippon") is an extinct genus of heteromorph ammonites. The species of Nipponites (primarily N. mirabilis) are famous for the way their shells form "ox-bow" bends, resulting in some of the most bizarre shapes ever seen among ammonites.

The ecology of Nipponites, as with many other nostoceratids, is subject to much speculation.