text: Another possible biosignature might be morphology since the shape and size of certain objects may potentially indicate the presence of past or present life. For example, microscopic magnetite crystals in the Martian meteorite ALH84001 are one of the longest-debated of several potential biosignatures in that specimen. The possible biomineral studied in the Martian ALH84001 meteorite includes putative microbial fossils, tiny rock-like structures whose shape was a potential biosignature because it resembled known bacteria. Most scientists ultimately concluded that these were far too small to be fossilized cells. A consensus that has emerged from these discussions, and is now seen as a critical requirement, is the demand for further lines of evidence in addition to any morphological data that supports such extraordinary claims. Currently, the scientific consensus is that "morphology alone cannot be used unambiguously as a tool for primitive life detection". Interpretation of morphology is notoriously subjective, and its use alone has led to numerous errors of interpretation.