I also rescued my first one from Walmart and it loved my tank. Very active and extremely cute. They grub around in the gravel with their tails straight up in the air. They don't really look like the photo shown, which I assume is a juvenile. They are mostly brown and have black and shimmery graphite-colored patches all along their body in almost a mosaic pattern. Really beautiful under the light. Keep in mind you need multiple corydoras of the same species. My original one used to chase his reflection until I bought it some buddies. Only downside is that they are kinda pricy at about $5 per fish for small ones.
This is "Salt and Pepper Catfish"(Corydoras habrosus). I think some people may be getting confused with "Peppered Corys"(Corydoras paleatus). They are sometimes also called "Salt and Pepper". Two different species. The "peppered cory" looks more like more common corydoras with some random coloration.