The pearl oyster!

From Spurgeon's sermon, "Love's Labors"

I wish, brothers and sisters, that we could all
imitate "the pearl oyster"--
A hurtful particle intrudes itself into its shell,
and this vexes and grieves it.
It cannot reject the evil, but what does it do but 'cover' it
with a precious substance extracted out of its own life,
by which it turns the intruder into a pearl!

Oh, that we could do so with the provocations
we receive from our fellow Christians,
so that pearls of patience, gentleness, and forgiveness
might be bred within us by that which otherwise would have
harmed us.