Answer:
Good memory, skin like the sea. A great beast I am, yet vermin frightens me. What am I?
I widen my jaws when you poke two fingers in me. I especially like to devour papers
I have 24 keys but cannot open any locks. Sometimes loud, sometimes soft. What am I?
I get paid when I drive away my customers. What am I?
I open to close but I close to open. I'm surrounded by water but I'm never soaking. What am I?
If you can spot one of these eastern warriors, it means they're not doing their job right.