Future Price of Eggs
There is a saying "but what does that have to do with the price of eggs?" This saying points to a universal truth that we depend on food to live. An egg is a concentrated easy to digest source of protein. The future price of eggs tells us how well society functions in the days ahead.
In times to come food will become scarce and very expensive. An egg is a measure of how dire the times will become. We see a bleak forecast for the far tomorrow unless we find cheaper more plentiful sources of protein.
In 2150's using astral time travel I saw blue green algae grown on waste as a food source.