Behold the work of ants. Wood ants are so amazing. They have a whole city in there. They make these massive mounds to better collect solar radiation and heat their nest.

On warm days in early spring when sun hits the mound they will come out en mass to warm their bodies in the sun. Then they run deep into the nest where the ground is still cold. When they get cold again they come back out and warm themselves again.

They heat depths of the nest in this manner.