a blotchy swellshark

a heptadecagon

biblical seventh day (of creation, of the Jewish week) / the seventh day (of the month, week, year, etc.)

Qitaihe (a prefecture-level city in Heilongjiang, China)

twenty-seven; 27

thirty-seven; 37

seventeenth day of the month

(mahjong) a 役 (yaku, “hand”) of seven pairs, worth 2 翻 (han, “doubles”)

the Seven Generations of Heavenly Gods, including 国常立 (Kuni no Tokotachi) of the first, 豊雲野 (Toyokumono) of the second, 埿土煮 (Uijini) and his sister 沙土煮 (Suijini) of the third, 角杙 (Tsunogui) and his sister 活杙 (Ikugui) of the fourth, 大戸之道 (Ōto no Ji) and his sister 大戸之部 (Ōto no Be) of the fifth, 面足 (Omodaru) and his sister 綾惶根 (Ayakashikone) of the sixth, and 伊弉諾 (Izanagi) and his sister 伊弉冉 (Izanami) of the seventh

(dated) milk / breast (of a woman, of a female mammal)