Poetry
Thanks Haiku

In and out, like the tides, I go.   Past the jaws, I move to and fro.   If you lose me, find me fast,  Or else my loss will be your last.   Question : What am I? Pronounced as one letter and written as three. Two letters there are and two only in me. I'm double; I'm single. I'm black, blue, and gray. I'm read from both ends and same either way. Question : What is it? See answer