The mantis shrimp delivers a punch so fast that the water boils and forms cavitation bubbles.
Why it is true
The mantis shrimp's punch reaches speeds similar to a .22 calibre bullet. When the appendage moves through the water, it creates cavitation bubbles that collapse and generate shock waves capable of breaking shells and even aquarium glass.
Source: AMNH
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.