When I was a kid, my neighbors cousin came to visit and he was all into bug collecting. Ya know where you make a board with pins and model all the bugs you can find. Put them in a jar with a cotton ball soaked in some kind of deadly crap.....then label all the different bugs.
This kid found bugs right in our two yards that none of us had ever even seen before. And quite a few that I don't think I have ever seen since. He had "Bug Books" as thick as encyclopedias, and there were bugs he caught that couldn't even be identified at that time. Totally alien creatures. Have you ever seen a centipede type thing WITH WINGS? Well bygod I have! (Once, about 50 years ago). If some of those creatures got to the size of a field mouse, or larger......it would be a scary world out there ! Especially for a guy like me that goes into shock at the sight of any spider bigger than a pea. 😅
It's pretty interesting that there are tiny critters out there in YOUR OWN YARD that nobody on earth is even aware of. And I bet the same situation exists in streams, ponds, and ditches.