From the movie Tremors, behold the graboid:
These are vicious, SUV to bus sized sandworms that have acquired a taste for human flesh. They are known to "swim" through the earth really fast too.
I know some characteristics the graboids have in the movies are unrealistic (their speed comes to mind). What I am interested in knowing is: how would a realistic graboid species look like? And how could such a species (the realistic, not the movie one) have evolved?
This question is part of the Anatomically Correct Series.