I was taking a walk with my dog at Okeeheelee Park like we do everyday. It was a very quiet morning. The sky was so beautiful because of all the different kinds of clouds, weather was warm and breezy out of the east. I happened to look up towards the sky (11:49 am),and saw this HUGE object over Okeeheelee Golf Course that is just to the east of where I was walking in the park. Trying to rationalize what I was looking at, I was thinking this is a huge strange kite? Blimp? I have seen many different types of planes, helicopters, blimps, drones, kites etc to know it was not anything like that. PBI and some heliports are not far from Okeeheelee Park so you see aircraft everyday. The object was cigar like in shape but it had like a dome/bump on the top half of it. Also, it looked like a row of windows on the side. What was really interesting is that it did not move or make any type of sound. I was about 500 ft away; and for its size you think you would hear sounds like aircraft make. I mentioned before about all the beautiful different types of clouds, well it was like this object was reflecting off of clouds to make it almost camouflage like if that makes any sense. The object was not in a cloud but many clouds around it. So some shine to it but also the dull grey of certain cloud colors. I have experience using x-ray equipment at airport security so very familiar with picking out shapes and objects. I continued walking east towards the object with my dog and did not take my eyes off of it until we got to the point in the path where we turn left/North to head towards parking lot and ::POOF:: it disappeared. Also at this time my dog became very wary, upset, his tail clamped down, curled up under him, and he starts pulling hard to the North. He wanted out of there bad! My dog does not behave like that normally, he loves the park, something was upsetting him. There were no other people/dogs around or golfers on that part of the course. Ironically on the 28 of May I brought my camera to the park to take photos of the Poinciana trees in bloom...ugh. But I tried my best to capture the UFO in a sketch I did when I got home.