Trilobites from the Pioche shale of Nevada are some of the oldest and most aesthetically pleasing and beautiful Cambrian trilobites from the American West. With a diverse range of species (some extraordinarily rare), these famous trilobites are a must for any collection.  O. fowleri is one such sought-after species due to its large size, rarity, nearly round cephalon, large eyes and dramatic spines.
 
Olenellus fowleri
Pioche Shale, 
Lincoln County, Nevada, USA
Early Cambrian
540-520ma