Spot the Difference

Matthias Schleiden and Theodor Schwann came up with the cell theory after observing cells for many decades. They determined that all living things are made up of cells, that cells are the basic units of structure, function and physiology, and that living cells can only come from pre-existing cells.

Carlsbad Caverns, located in New Mexico, was created by sulfuric acid instead of water erosion, as is the case with most limestone caves. The caverns are home to as many as 300,000 Mexican free-tail bats that stream out of the caverns each night in search of food.

The original word for bear has been lost. In the medieval period, people believed that simply uttering the animal’s name would summon it, so they used a euphemism that meant “the brown one” and the original word, which had never been recorded, soon disappeared.