Terebridae are not variable in shape: they are all slender and pointed. The variability in sculpture and pattern is impressive. Their determination is a challenge and we are fortunate with the existence of the work of Bratcher and Cernohorsky (1987). There are about 350 species.
For a list of genera and species:
http://www.marinespecies.org/aphia.php?p=taxdetails&id=160424