Answer:
As I walked along the path I saw something with four fingers and one thumb, but it was not flesh, fish, bone or fowl.
Who is it that rows quickly with four oars, but never comes out from under his own roof?
If you spot one of these eastern warriors, they're not doing their job right.
There are millions of me. I am very small but when moving fast I am deadly.
What comes once in a minute, twice in a moment, but never in a thousand years?
Who makes it, has no need of it. Who buys it, has no use for it. Who uses it, can't see it. What is it?