Tortoises are famously slow moving, but have you ever wondered why they crawl along at such a glacial pace?
According to Mental Floss, there are actually a number of reasons why many of them have maximum speeds shy of 1mph.
One is that they only eat plants, so since their body isn't fast moving, they don't have to be either.
But that's not the only reason.
Find out more in the video above.