Assertion: narwhal's tusk | /r/CapableOf | indicate fertility
Facets:
Source sentences:
text: The narwhal’s mating rituals are unknown; however, some scientists speculate that the “horn” on male narwhals has the sole purpose of being used in mating rituals, as recent studies have proven “that the bigger the tusks, the better the testes, pretty much—tusk length and teste mass (which indicates fertility) were closely related” (http://time.com/3419809/narwhal-tusks-fertility/).