Fast, low flying white cloud with object inside turned into triangle craft then shot off.

A strange white cloud moving low and fast was spotted over ocean. It looked like a white school bus shaped object inside a cloud. It all moved as one. I grabbed my phone as it changed shape into a swirling pattern. Then the front became a reflective triangular object. The triangle shot off in the blink of an eye, leaving the cloud part behind. The cloud stopped moving, turned grayish, and slowly disappeared.