For those not in the know (like me!), a link to info on the Tsurukame app.
P.S.: I looked up ‘tsurukame’ on Jisho.org and found that it has a few distinct and interesting meanings! tsurukame - Jisho.org
From Jisho.org
鶴亀
Noun
- crane and tortoise (symbol of longevity, artistic motif) See also 鶴は千年亀は万年
鶴は千年亀は万年
Expression
- enjoying a long life is a matter for congratulation; cranes live for 1000 years, turtles live for 10,000 years
Proverb
鶴亀算
Noun
- obtaining the respective numbers of cranes and tortoises from the total of their heads and legs; calculating the values of two unknown quantities from their unit total and the total of one of their attributes
鶴亀鶴亀
- knock on wood; touch woodspoken to ward off misfortune