This modern Greek sponge seller displays his 

 wares as did his ancestors more than twenty 

 centuries ago. Of the 2500 species of 

 sponges, only a half dozen or so are 

 suitable for household use. Once regarded as 

 a plant, sponges actually are the dried 

 skeletons of a primitive marine animal. 



another. It was not until 1922 that he completed the job of plotting 

 the migrations of European eels and discovering their spawning 

 ground. Thus he finally solved a problem that had occupied scholars 

 for more than two thousand years. 



Like the eel, sponges have been fished for well over two thou- 

 sand years. Evidence of their use goes so far back that we can 

 assume they were familiar household articles in the earliest Medi- 

 terranean civili2ations. They have been of such value to trade, art, 

 and medicine (for their iodine content) that one scholar has sug- 

 gested a possible link between the rise and fall of civili2ations and 

 the number of sponges used. Even today, however, there remains 

 a degree of uncertainty about the exact nature of this marine 

 organism whose dried skeleton has proved so useful to man 

 throughout the centuries. 



First of all, there has always been some confusion over the use 

 of the word "sponge." There are at least 2500 species of sponges 

 and they are found on the ocean floor in all seas, from pole to pole, 

 and at all depths. But only a half dozen or so of the 2500 species 

 can be used in your bath, and these are concentrated mainly in the 

 Mediterranean and around the Bahamas and Florida. What zs the 

 household sponge? Aristotle correctly guessed that it was the 



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