This is a didemnum molle, which is a species of sea squirt. A couple more pictures below:
Portuguese man of war Despite its outward appearance, the Portuguese man o’ war is not a common jellyfish but a siphonophore, which is not actually a single multicellular organism, but a colony of specialized minute individuals called zooids. These zooids are attached to one another and physiologically integrated to the extent that they are incapable of independent survival.
סלומה 