UFO question......................…

i am being legit, when i say UFO i dont mean little green men from mars. I mean i was out one night near the beach and directly over one of the hotels, maaybe 500 feet above, i see approximately 10 christmas light blue pulsating lights around the perimeter ( really the bottom of it) of a concave isosceles triangle shaped craft. it was just hovering there for a half hour or so (that was the length of time it was there since i only saw it briefly then went to the store and back). I want to know if anyone has seen anything like this too and possible explanations. can give more details if needed