Job, the oldest book in the Bible mentions them as Leviathan. The Six Days of Creation:
What if everything you see in the world around you is God's eternal decree made visible by his creation of time, space and matter?
In Hebrews 11:3 the writer says; “By faith, we understand that the worlds were set in order at God’s command so that the visible has its origin in the invisible.”
Calvin translates it; “so that they became the visibles of things not visible,” or, not apparent. And then says; “thus the same truth is taught here, as in Rom. 1:20, where it is said, that the invisible things of God are made known to us by the creation of the world, they being seen in his works.”
So are we looking at eternity made visible through the matter God created to make it visible? And this can easily fit into 6 literal days. Because the distances and age were already here. Only now made visible 6-7000 years ago.
The same way metal shavings when dusted on a piece of paper with a magnet below, reveal the magnetic waves. Like a huge house, light-years across. Where God applies matter and all the lights come on at once. Taking moments for what would take trillions of light-years using space-time measurements?