Whale poop contains iron that may have helped fertilize past oceans

A recent theory proposes that whales weren't just predators in the ocean environment: Nutrients that whales excreted may have provided a key fertilizer to these marine ecosystems. Oceanographers now find that whale excrement contains significant amounts of iron, a vital element that is often scarce in ocean ecosystems, and nontoxic forms of copper, another essential nutrient that in some forms can harm life.