What is the grinding plates in the platypus bill?

The grinding plates in a platypus bill are specialized structures made of keratin, which help the animal process its food. When the platypus forages underwater, it scoops up mud and small invertebrates, using these plates to crush and grind its prey. Unlike teeth, these grinding plates allow the platypus to effectively break down food without the need for traditional chewing. This adaptation is crucial for their diet, which primarily consists of insects and crustaceans.