Picture this. I have a flat set trap on a trail, no (intended) scent or lure, just buried on a small crest at a step over a stick. It brought one coyote and 2 foxes last year.
25 yards away is a trail camera I occasionally toss house scraps in front of, no more than once a week... fish skins, chicken bones.... moldy items... nothing intentional just what I may not want in the trash.
I placed a pile of snow crab shells out there a few days ago.
2 days later, sitting directly on top of the buried trap 25 yards away from the dump pile was 2 large pieces of crab shell.

The animal probably has a trail camera watching your reaction