some of the special structures in the members of these phylum as follows:
Members of porifera are sponges. they have collar cells and cellular -level body organization. Cnidarian have stinging cells present on the tentacles around the mouth. Ctenophorans have comb-like plate cells for swimming. Platyhelminthes - members are first to have sensory and nervous tissue in the head region.
Well it happens every six months, one in summer in June and winter December. And if i'm wrong then i understand :) <span />
Answer: atoms come from originally....The first source was the BIG BANG that created the Universe 14 billion years ago. When the big bang occurred, the elementary particles initially were too hot initially to make any stable atoms... but after a few thousand years, when things cooled down a lot, Hydrogen and Helium got made.
