The large rock in the photo above is a very special rock. It is known as the Rosetta Stone, and it is the showcase exhibit in the British Museum in London. It's technically just a rock with some scratching on it, but it was responsible for our learning how to decode Ancient Egyptian hieroglyphs.

How? Because it was a decree issued in Egypt in 196 BC. Specifically, it was issued in three different languages (Ancient Greek, Demotic script and Egyptian hieroglyphs) and thus was the key to our being able to figure out the previously indecipherable language of Ancient Egypt. It was like capturing the other side's code book in WWII.

Which means this rock was literally a key to unlocking a heretofore opaque ancient language.