Some scientists theorize that comets may have played a role in delivering the building blocks of life to Earth. As icy bodies traveling through space, comets contain water, organic molecules, and complex carbon compounds. When they collide with planets, these materials can be released, potentially seeding environments with the ingredients for DNA and other essential biomolecules. This idea, known as panspermia, suggests that comets could have acted as cosmic couriers, spreading the raw materials for life across the universe.