Well nature has done a pretty good job building mobile computerized machines out of flesh and blood so I guess the soul is not much different except for a few specialized features. It's probably a lot smaller than the period at the end of this sentence, subatomic, kind of like a microchip, a Pentium 500+. Tiny yes, invisible too, but able to cross the boundaries between the real and the surreal, the natural and supernatural and so on.
There's zillions of them out there. Alas, nature is not perfect and occasionally the soul of a dung beetle accidentally ends up in a human's body, probably a guy who ends up working for Port-a-Potty. You don't want to know where a philosopher's soul usually ends up. You didn't know this but mass extinction epochs on Earth usually occur when souls go in to upload and reprogram.