I remember reading a book when I was a kid (age 7-9) about squirrels (or maybe other small animals) that were using the octal numeral system.
Counting to 7 (since 8 = 0) was a whole new magical world that opened for me back then, until I found out a bit later that this numeral system existed for real.
A quick search on the internet gave me nothing, but maybe you can help?