A reference to “tiny pebbles” that grow into boulders is found in the Japanese national anthem Kimigayo, which is based on Waga Kimi wa (“My Lord”), a celebration song dating back to the early Heian period.
There are several of these boulders, known academically as calcareous breccia, on the shrine grounds. In geological terms, they are produced when limestone is dissolved into milky liquid by rainwater and then forms huge masses with sand and stones of various sizes.
Sazare-ishi means “tiny stones,” and boulders formed from such tiny pebbles are considered auspicious rocks representing prayers for the Emperor’s long reign.