Definition: The term "neorhynchus" refers to a type of paleontological fossil that is characterized by its thin, irregular surface and its lack of a central chamber or cavity. These fossils are often found in sedimentary rocks and can be found in various environments, including the ocean floor. Neorhynchuses were once thought to be extinct but have since been rediscovered as they can be found at sites such as the Grand Canyon and the Amazon River.