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Phylum  ANNELIDA
Worms are an ancient group that, apparently, dates back to the Vendian (nearly 700 MY back). Ranging in size from microscopic to eighty feet long, worms come in all sizes and shapes.  They make up some 3% of the animal kingdom.  Some are segmented, some are not. Lacking hard parts, their bodies are not commonly fossilized, but microscopic worm teeth are often found in rocks.  They will not be discussed here.  However, some worms tracks and  burrows are common in the fossil record, and worm tubes and masses of these tubes may occasionally form reefs.