Copro Pebbles?

Fossil Type: 
Inclusions: 
Gastroliths
Composition: 
Location: 
Henry Mountains UT
United States
Utah US
Formation: 
Period: 
Dimensions: 
4 1/4" x 4 1/4" x 3 1/4" (2 lbs 2.1 oz)

It is unclear whether rocks such as this have a fecal origin. Small pea gravel is present on its underside. If it is a coprolite, this could be a result of the material it plopped on or, if others are present on the inside, they could be gastroliths. My best guess is that this is not fossilized poop.