The tongue of a blue whale weighs approximately as much as an elephant.
Why it is true
The blue whale is the largest known animal on Earth, and its tongue alone can weigh about two thousand seven hundred kilograms, which is equivalent to the weight of an adult African elephant.
Source: Marine Biology
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.