When I was little my uncle told me all about the glass shark that lives in swimming pool drains. He said because it was made of glass, you couldn't see it except as shifts in the current/pool lights. Of course, wind on the water causes these shifts as well. Thanks, Unc.
A childhood belief about swimming pools

others believed things like this
- I used to think that a "pool shark" was an actual shark that lived in a swimming poolAnon
- When i was younger,I used to believe i could see a shark in a pool .Anon
- I believed that the ladder on the back of a trailer/rv led up to a swimming pool.— marilese
- I used to believe that if you farted while swimming in the pool, it could propel you foward really fast.— Rick
- Up until I was in 3rd grade I believed my bathing cap is what kept me afloat in the swimming pool! Anon
- When I was a kid I used to think the "carpool lane" was an actual pool cars went swimming in— skeez