I think that the tulips grow under snow because they can grow under cold weather to the temp. So that is why I think they can grow under snow.
Tulips grow under the snow because after the snow is gone it's spring.
At spring time the tulips should bloom. So they are able to be pretty. Flowers that were planted in September an dshould bloom in March or April. The tulips don't know there is snow so they just keep on growing. Also because it's warm and they push there way up.