Answer:
Spontaneous generation / abiogenesis
Explanation:
Long ago, philosopher still debating where did living organism come from. Aristotle came up and hypothesized that living being can come from inanimate matter (without any genetic transfers from the parents of that particular organism) . This theory called spontaneous generation.
Spontaneous generation had later on proven to be false and living being is not spontaneously created, but come from reproduction of the same species which passed on their genes to the next generation.
Useful for dating and cossetting the strata of which the fossil is found in
Due to a law being a predicted sort of event that is bound to happen every time, a pattern, we can say that since the cell theory is a pattern instead of a possible explanation, it can be a law. However, since we don't have an accurate explanation to the part which claims that they all come from pre-existing cells, it is a theory, we don't have enough information to confirm that the theory is a solid fact, therefore, we can't confirm that it is a law.