Many First Nations teachings, including those of the Anishinaabe and the Haudenosaunee people, use the back of a turtle’s shell as a lunar calendar.
Depending on how we measure a lunar month, the moon goes around the earth in approximately 28 days. This means that in one year (365 days), the moon goes around 13 times, giving us 13 lunar months with 28 days each.
Conveniently, if we examine a turtle’s shell, we find the same pattern of numbers of lunar months in a year and days in a lunar month:
For more information on the turtle shell lunar calendar, please refer to the following sources: