Simplify the following text for a Grade 6 native English-speaking person.
Original: Sizes range from 5 mm ( 1\/5 '' ) for some tropical species to 15 cm ( 6 '' ) for the tiger cowry , Cypraea tigris .
Simplified: Lengths range from 5 mm for some species up to 15 cm for the tiger cowry , Cypraea tigris .