Bananas aside, I've always thought that Wal-Mart was a life form similar to the one described by Stanley Weinbaum in "A Martian Odyssey". I'm referring to the enigmatic rock pyramids that the protagonist and his Martian buddy Tweel trace across the Martian plain. The first are very small, ancient and the tops have been broken open. As the protagonist and Tweel continue, the pyramids grow larger and larger (and younger) until they encounter the last one which is still capped, i.e. inhabited.

Wal-Marts tended to exhibit the same behavior -- at least in my native Arkansas -- moving to a larger facility while leaving the older, empty shell vacant. Oh, it's true -- opportunistic creatures going by the name of Sam's Club or Bud's sometimes took over these empty shells, but one could usually trace the pattern of movement of a town's Wal-Mart by the empty storefronts left behind. I suspect that Wal-Mart has entered a new stage of their life history or perhaps the species has evolved since many of the stores now grow by simple expansion into a Super Wal-Mart.