Passage Summary: Geologists found some rock markings that look like worm tracks, but because the rocks are way older than any worms we know about, they assume the marks must just be a natural geological fluke.

Conclusion: The marks found in the sandstone are likely the result of geological processes rather than the tracks of ancient worms.

Reasoning: The marks date back to over half a billion years before the earliest known evidence of multicellular animal life.

Analysis: The argument relies on the assumption that our current timeline for the evolution of multicellular life is definitive. To weaken this, look for an answer that suggests our timeline is incomplete or that these specific marks possess features that only a living organism could produce. If we discovered that multicellular life actually existed much earlier than previously thought, the geologists' primary reason for doubting the worm theory would vanish.