The pearl

There was a very lovely pearl
who yet had to be found.
Between two covers it did twirl
impatiently around.

One day there came a fisherman
and made it to the clam.
And that was just the treasure's plan,
one day to pass exam!

The moment that clam opened up,
it yelled to that poor son,
Don't ever put me in a cup!
By that its luck was done.