South of Glendive MT
See map: Google Maps
These fossilized crustacean burrows are lined with pellets. These pellets can have a fecal origin or can be sand/silt cemented with oral secretions (think spit balls). This practice is used by modern ghost shrimp and other crustaceans when building burrows and in soft sediments. These particular specimens don't appear to be lined with coprolite pellets.