When the vast armada left its dying home in search of a young one, they were infused with hope and excitement. Their elaborate biotechnology had given them fleets of huge biocraft for transport to the similar but distant planet. Travelling just under the speed of light, it didn’t seem long to them, but it was millions of generations back at home. Finally, they landed on their destination.
They were shocked to find the new world huge, much bigger than expected; unable to dominate, they stayed in their self-propagating ships contemplating their error: apparently, size reduction from near-lightspeed travel is permanent.