Animal

They're actually great swimmers now, but later they will become excellent hoppers.

related riddles

A warrior amongs the flowers, He bears a thrusting sword. Able and ready to use, To guard his golden hoard.

In the fields a frightful thing. Watch it and you will find, it has a pitchfork in the front, and a broom back behind.

A pony trots his way through the world on these.