Assertion: halibut | /r/AtLocation | gravel
Facets:
value: usually
type: DEGREE
value: on rock bottom
type: LOCATION
Source sentences:
text: They are usually found on sand, gravel, or clay, not on soft mud or on rock bottom; 400-500 fathoms may be set as the lower boundary to their existence in any numbers, but their absolute depth limit is not known.