We can't know if it's significant at all based only on the fact that we haven't seen it yet. It seemed pretty significant that Europeans had only seen white swans, to the point where the concept of 'black swans' was a jest, like "when pigs fly!". Then they got to Australia and found black swans. The black swans had been there before English was even a language.

The simple fact of not having seen something is totally baseless as evidence to whether or not that something is possible.