Flood Blood Symbols
From Halopedia, the Halo Wiki
The Flood Blood Symbols are a Halo 2 Easter Egg on the level, Quarantine Zone.
[edit] How to find
When you start the level, turn back through the cave you came through in the previous level, and go across the shattered bridge. Then look at the splotches of Flood blood. While many of them may seem random, they are distinctly some sort of symbol, some of them like the Marathon symbol, while others more sinister.
