Examples of such designoid objects include the hedgehog and the spiny anteater (both of which evolved pointed spines along their back) and the marsupial wolf (which looks like a dog but is actually a marsupial). He illustrates the reason why convergent evolution occurs by using two small models of commercial aircraft. The reason they look similar isn't due to industrial espionage, it is due to the fact that they are both built to fly, so they must make use of similar design principles.
The hedgehog and spiny anteater serve as examples of designoid objects that have evolved pointed spines for defense. The marsupial wolf, which resembles a dog but is actually a marsupial, also illustrates convergent evolution. This concept is explained through the use of two small models of commercial aircraft, demonstrating that similar designs emerge when different organisms are adapted to perform the same function.