Wildlife biologists urge anyone who hopes to catch a glimpse of ‘Snowball’ to keep their distance and avoid interfering with it. Says one: ‘If the bird is looking at you, then you’re too close.’

The black substance was staining the feet of people at the beach, prompting one local resident to alert state officials.

The Maine Marine Patrol said the shark was seen swimming just outside the jetties at the mouth of Wells Harbor around noon Thursday.