Or, for a medical example, suppose smoking multiplies the risk of lung cancer by some number R: then the Wald test can be used to test whether R = 1 (i.e. there is no effect of smoking) or is greater (or less) than 1 (i.e. smoking alters risk).
There are more than 900 species of Tardigrade or Water Bear, pictured. They're found everywhere in the world, from the highest mountains to the deepest oceans. Boil the 1mm creatures, freeze them, dry them, expose them to radiation and they're so resilient they'll still be alive 200 years later.
Tardigrades, also known as water bears, are some of the most fascinating animals in world. The creatures can survive tremendous heat and cold, radiation and vacuum. The animals, pictured, can live happily in the most extreme conditions. This Tardigrade or water bear comes from Roan Mountain, Tennessee.