I found a metallic black worm in my bathroom?

i found a black almost metallic worm on the floor of my bathroom. it was about 3 inches long and very slender. it moves almost as if it's swimimg. i'm not sure wether it came from my clothes bin or has been living in my bathroom. I live in FL and it's very humid around the summer. what kind of worm could this be and should i be worried?