Assertion: porpoise's fin | /r/HasProperty | dark gray
Facets:
value: its back
type: LOCATION
Source sentences:
text: They have a triangular dorsal fin, a dark gray back, and a white underbelly.
text: Its back, tail fin, dorsal fin, and flippers are dark grey, while its underside is whitish with some grey stripes which run along its throat.
text: The back, flippers and dorsal fin are dark gray while the belly is a much lighter whitish color.