gray shaped like 1/3 ball top of disk rotated but not 360 degrees it roated clockwise then counter clockwise several degrees moving very slow had slight wobble a stainless steel round tract supported the dome the dome rotated on this tract a wheel the same color of the dome rolled forward and backwrd on this silvertract the underside had several markings on the bottom of the disk the disk was about 10 yd.aas it passed over me at a height of about 100ft.it proceeded to the far end of the lake where it dipped right and peeled off to the left and disappeared behind trees it made a slight whirring sound