Authorities have warned beachgoers to be wary of a particularly large invader with a potentially deadly sting.
Driven towards the British Isles by a recent bout of stormy weather, the Portuguese man o'war - which despite resembling a jellyfish is actually a siphonophore - can grow up to 160ft long and is able to deliver a sting that, on rare occasions, can actually prove fatal to anyone on the receiving end.
Also known as 'bluebottles' or the 'blue bottle jellyfish' due to their strikingly colored bodies, these enigmatic creatures are unable to move under their own power but instead go where the wind and tide take them - which in this case happens to be the beaches of the south of England.
Its sting, which can be delivered long after the creature is dead, can induce excruciating pain.
Man o'wars are particularly interesting because they are not single creatures but are instead made up of colonies of smaller creatures known as zooids.
The name comes from a type of 18th-Century warship often used during large naval battles.
"The Portuguese man o'war lives at the surface of the open ocean, held afloat by a gas-filled bladder," said a spokesperson for the Wildlife Trust.
"This has a crest-like structure at the top which acts as a sail. They can't swim and are at the mercy of the winds - which is why they often end up washed ashore after big storms."