What was discovered during napoleon's expedition to egypt in 1799 ce that was of immense importance in understanding and interpreting egyptian hieroglyphics?

Rosetta Stone was discovered during Napoleon's expedition to Egypt in 1799 that was of immense importance in understanding and interpreting Egyptian hieroglyphics.

The Rosetta Stone is a granodiorite stele, found in 1799, inscribed with three versions of a decree issued at Memphis, Egypt in 196 BC during the Ptolemaic dynasty on behalf of King Ptolemy V.