Clearly Isaac Hayes drew his inspiration from the limpet Crepidula fornicata for this classic funk soul hit. Crepidula, known as a slipper limpet, is a sequential hermaphrodite. During the same course of life, this limpet will change sex from male to female.
The larger ones on the bottom are female while the smaller ones on top are males, just waiting there turn to turn into females and be at the bottom of the pile! They can stay this way for a looooooooooong time and budge. The snail on the bottom still moves around with her half dozen or so hitchhikers. This sexual position is even captured in the fossil record as evidenced by Flickr user bibliona. The Seal Rock strata in coastal Oregon dates from the Miocene to the Pleistocene. I would like to thank bibliona for making this fantastic example available in a Creative Commons license.