Answers

2016-02-28T10:20:43+05:30
They have spongy covering to prevent themselves from dessication.
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2016-02-28T10:30:33+05:30
The first animal to appear on Earth was probably the sea sponge. sponge have appeared on the Earth much earlier than any other animals. there bodies are spongy cover to take oxygen in water and the other animals should not damage them.
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