Crab and shrimp: they’re not just for dinner anymore. A natural polymer found in the exoskeletons of crustaceans can keep your car cleaner. Never heard of chitosan? You may not be able to say that for long. Researchers in the School of Fashion and Textiles at RMIT are using the biopolymer, found in the exoskeletons of crustaceans such as crabs and shrimp, to coat the 100% polyester fabric used in automobiles. Combining fragrant oils with the polymer, which has the ability to form an antimicrobial film, creates a durable, fragrant finish in the fabric.

Based on this passage, crabs and shrimp are _____________.