Baleen is made of , the same fibrous protein found in human fingernails, hair, and animal horns. Each "plate" is actually a sandwich-like structure: Lessons from the Ocean: Whale Baleen Fracture Resistance
Baleen is a biological filter-feeding system found in the mouths of baleen whales (Mysticetes), such as humpback, blue, and gray whales. Unlike most mammals, these whales lack teeth, instead possessing hundreds of large, flexible plates that hang from their upper jaws to sift tiny prey from seawater. Composition and Structure baleen