How did life forms change before the
end of the Precambrian Eon?

Explanation:

New varieties began to harness the power of the sun through a biochemical process known as photosynthesis—a move that would ultimately lead to simple plants and which opened the planet up to animal life. Some three billion years ago, the Earth's atmosphere was virtually devoid of oxygen.

ecological efficiency: % of usable energy transferred as

biomass from one trophic level to the next typical is 10% efficient (90% of

energy is lost),is diagramed as the pyramid of energy flow. then osprey eagle

are tertiary consumer and the shrimp are primary consumer, so to balance

mass of shrimp (1/0.1) / 0.1 = 100 kg