Beachgoers on Cape Cod have another thing to be aware of: The Portuguese man-of-war has returned.
If touched, the creatures can deliver an extremely painful sting. Several of them have been spotted in recent days.
Some washed up on Sea Gull Beach in Yarmouth, Massachusetts, over the weekend, and another was spotted earlier this week off Stage Beach in Chatham.
The Woods Hole Sea Grant on Wednesday encouraged area beach officials to post warning signs.
The Portuguese man-of-war can often resemble floating plastic bags and are sometimes mistaken for jellyfish.
They have been visitors to the Cape in past years. Several people were stung in 2013, but there have been no reports of any painful encounters with swimmers so far this summer.