Answer:
What can be swallowed, but can swallow you?
It comes only before, it comes only after. Rises only in darkness, but rises only in light. It is always the same, but is yet always different.
Power enough to smash ships and crush roofs. Yet it still must fear the sun.
Hold these between your knees if you want to set a Cuban beat.
I count time, but have no end. Tick tick, but I am not a clock. What am I?
The sun bakes them, The hand breaks them, The foot treads on them, And the mouth tastes them. What are they?