Answer:
I am the yellow hem of the sea's blue skirt.
I am your mother's brother's only brother in law. Who am I?
I'm the son of water but when I return to water I die. Who am I?
What is something you can hold without ever touching?
They are the shore's gallant knights.
It flows out of the soil, It burns you if it boils, And holds us in its coils, More valuable than gold, As black as it is old.