How does Scott O'Dell use imagery in The Black Pearl?

Imagery:

"The shells were the largest I had ever seen. They were half the length of my arm and thick through as my body and covered with weed that looked like a woman's hair. I choose the nearest one, which seemed to be easier to get at than the others."

"I first saw the outstretched wings and then he passed the boat and I saw the amber eyes turn and look at me as they had once before. They said as clearly as if the words were spoken, 'The pearl is mine. Throw it into the sea. It has brought you ill fortune and ill fortune will be yours until you give it back."'

"Outside, the sun now lay golden on the roof tops and the big bells were still ringing over the town. They rang in my heart, also, for this new day was the beginning day of manhood. It was not the day I became a partner in the House of Salazar nor the day I found the Pearl of Heaven. It was this day."