Some anemones can sting and be poisonous to humans. In some waters of the world though, much like the Daddy Long Legged spider, the anemone can still be poisonous, though not be able to inject poison into humans. This is the case with anemones on the Western US Coastline (Washington to California). As a child i grew up playing with anemones on beach days without any problems. In tropical waters and other locations, anemones stingers are able to pierce humans' skin and inject the anemone's toxin. Much like a bee sting, a few can simply be painful while enough could kill you. I don't know about allergens to anemones much like people can be to bees/foods/etc. If you are swimming in unfamiliar waters or simply playing by the beach, do some research before hand. Better safe than sorry :)
Yes, they can kill you, but it is very rare and it depends where they hurt you and how your body reacts to their venom.
sea anemones do not have shells !
are sea anemones decomposers
Many species of wentletrap sea snails attack sea anemones. Some species swallow small and juvenile sea anemones whole, while others apparently nibble on tentacles and tissues of large sea anemones. Many sea slugs that prey on sea anemones, such as the rainbow nudibranch, Dendronotus iris, do not kill their prey, but merely shear off a few tentacles with each attack.
Sea anemones are consumers yes.
any color at all
You can find sea anemones on the bottom of the Sea. Sea anemones stay in one stop there hole life.
sea anemones live in groups
yes sea anemones have a nerve net.
Some sea anemones get to be 100 years old.
the sea anemone have radial symmetry
Anemones' are located in the sea :)