I saw what I thought was a plane flying in the distance, I watched it for about 4 seconds when it abruptly disappeared.

I was in the car, my friends and I were driving back from paddle boarding in penn cove, towards Boon Road. I was looking out the window and saw what I thought was a plane. It was white/greyish and it was flying the same direction we were going. It was a cylinder-like shape and it was tilted slightly up, I genuinely thought it was a plane. After four seconds of looking at it, it disappeared extremely fast. It was there and then it was gone. It was blue clear skies, there was clouds up ahead but not close enough for the craft to disappear into.