👉 The oldest fluid known to science is likely a primordial, or ancient, form of water that existed during Earth's formation approximately 4.5 billion years ago. This primordial water was not the same as the freshwater we use today; instead, it was a dense, high-pressure liquid that likely existed in the planet's mantle. Scientists infer its composition based on isotopic analysis of ancient zircon crystals, which contain water trapped within their crystal structure. These crystals suggest that the water was rich in deuterium (heavy hydrogen), indicating it formed in a hotter, more energetic environment than today's oceans. This ancient water played a crucial role in shaping early Earth's geology and potentially contributed to the development of life by forming oceans and influencing atmospheric conditions.
