I am not alive, but I grow. I don’t have lungs, but I need air. I have no mouth, but water kills me. What am I?

In a flock of brethren, I arrive. In shallow waters, I take a dive. I come out with a fish to eat, then on the beach I rest my feet.

I sound like a mistake, but I do not sound like silence. You might hear me in a clap of clouds.

Down in Florida, I help grow islands of great girth Unique to my kind, a plant that gives live birth What am I?

You may lie on me as I am your seat I keep you off the ground, even your feet Although of my kind there are differing sorts I prefer it when trees are my supports