Seashells whispered secrets to the sea.

Meaning: This is a creative way of saying that the seashells were making soft sounds as they moved in the water.

Choice of Words: Whispered means to speak very softly. Secrets are things that are kept hidden. Sea is a large body of salt water. When you put them together, "Seashells whispered secrets to the sea" means that the seashells were speaking very softly to the sea, sharing hidden things.