When I was a kid, I found 2 salamanders outside in our yard. I made a terrarium from natural materials, put the lid on the pretty decent-sized terrarium... and after the first night... they were completely gone. I never solved the mystery. They probably crawled into the walls somewhere and then realized that the grass was not greener on the other side. I don't know how they got out, unless they put on an invisibility cloak to fool me.