The function of the limb is to help them get around and move. They might be similar in the way they’re structured? I don’t have a picture so I can’t tell. And you can assume that at one point these four animals all shared a common ancestor. Hope I helped!
Compound: two or more different atoms chemically bonded together. Molecule: two or more different or same atoms chemically bonded together. A mixture: contains two or more substances that are not chemically bonded together Hope this helps!!!!!!
