Sponge
Like cnidarians (jellyfish, etc.) and ctenophores (comb jellies), and unlike all other known metazoans, sponges' bodies consist of a non-living jelly-like mass (mesoglea) sandwiched between two main layers of cells. Cnidarians and ctenophores have simple nervous systems, and their cell layers are bound by internal connections and by being mounted on a basement membrane (thin fibrous mat, also known as "basal lamina"). Sponges have no nervous systems, their middle jelly-like layers have large and varied populations of cells, and some types of cells in their outer layers may move into the middle layer and change their functions.
Jellyfish stings in Australia
Jellyfish stings in Australia can cause pain, paralysis and death for swimmers with exposed skin. Numerous venomous species of jellyfish occur in Australian waters, including the box jellyfish and Irukandji Jellyfish. Box jellyfish are believed to have caused at least 69 deaths since record keeping began in 1883. Although they are commonly mistaken for jellyfish, bluebottles are actually siphonophores.