FFO Name: Rosetta Stone
"Stone tablet etched with ancient inscriptions."
The Slab is found in the Sea Shrine. Take it to Dr Unne to learn Lefeinish.
The Slab is called the Rosetta Stone in the Japanese version. The real Rosetta Stone is a stone tablet found near Rosetta, Egypt that had the same message written in 3 languages and led to the understanding of Egyptian hieroglyphics. It returns in at least FF8.