Swimmers weren't the only ones in the water at Horseneck Beach this weekend.
NBC 10 reports that warnings signs about the dangerous jellyfish-like creatures have been posted at the popular Westport beach, though there have not been any reports of beachgoers being stung...yet.
The large, blue-ish/purple jellyfish are often found floating on the water's surface or washed up on shore.
They can have tentacles up to 30 feet long and can cause a seriously painful sting whether they are alive or dead.
Of course paying attention to where you swim is very important, but watching where you walk on the beach is also key. The Portuguese Man of Wars can wash up on shore and be harder to see when they are covered in sand.
The venomous sea creatures have also been spotted out on Cape Cod in the last few weeks.