By one definition, they must be. That is, anything not large enough to be shaped “roughly round” by its own gravity is defined to be not a planet, but something else (like an asteroid).
I remember Carl Sagan on Cosmos being asked this question by a kid at an elementary school, and he showed a picture of an asteroid, IIRC, and described it as “a lumpy world”!
I always thought the Watcher’s head was kind of round.