A blue whale’s heart can be as large as a small piano.
A whale’s heart is not the size of a car. The blue whale’s heart needs a better metaphor! What else weighs about 400 pounds?
A blue whale’s heart is almost as big as a small piano.
A blue whale’s heart is almost as big as a Harley-Davidson.
A blue whale’s heart weighs about the same as a (filled-up) oil drum.