Some seeds need dark and some need light, but they all need moisture. Once the conditions are just right, the plant inside the seed starts to grow and get bigger. It pushes open the seed coat, kind of like a chick hatching out of an egg.
Once it has popped the seal, air can get to the seed – and things get serious! Watch this time-lapse video of an acorn seed growing and get gob-smacked by the genius of germination!