Goldfish
Fish know the purity of water as liquid in every direction they can go with no friction and just motion. There was a pet store that was close to my home that I would go with my daughter, and it specializes in fish called Pearlscale. When my child was young near the house there was a fish store which specialized in various types of Asian fish, these are the ones we thought particularly funny. So we would go to the store at least once every month.
