We have once already (July 2005) advertised for OEDILF (the Omnificent English Dictionary in Limerick Form), and now it’s time (summer-time) to do it again. Here’s mephistopheles‘s simple explanation of a cell membrane:
The membrane designed to divide
Extracellular stuff from inside
Does exceedingly well
At defining the cell
With a border two molecules wide.
Much more here.