The "Rosetta Stone," named for an important archaeological discovery from pre-Expansion Earth, is a titanium alloy monolith that contains the same message in two alien languages. Presumably its purpose is to teach one species' language to the other.
—Approximately 250 years old —Structure mimics Architect block construction as discovered on 4546b —Emplaced on limestone tabletop above water-carved alcoves —Projected lifespan: unknown
The known text on the monolith is written in Architect Linear, first translated by Architect devices discovered on 4546b. Architect Linear is remarkable for its extremely clear, unambiguous grammar and lack of context: it behaves like a programming language designed to compile on a wide range of hardware. Since first contact on 4546b, all Alterra intelligences have been programmed to translate Architect Linear for their users. It is unlikely that Architect Linear can be spoken aloud.
The unknown text is written in a glyph system provisionally designated Axum Radial A. This system is logographic: each glyph represents an entire word or concept. Discovering additional glyphs will help translate more complex Axum texts.
Conclusion: the Axum left this monolith as a message to Architect visitors. Be alert for signs of Architect activity, including robotic constructs and samples of kharaa bacterium.