 Material coincidence may explain how spatial coincidence is possible, but what about material coincidence itself? On the face of it, the claim that different things can be made up out of the exact same parts is no more plausible than the claim that different things can be located in the exact same place. We will call this the extensionality objection, since it appeals to the common idea that wholes are individuated by their parts in the same way that sets are individuated by their members.