A calmness before I arrive but be careful for something will surely fly

I start unseen in depths so far, yet end up shining like a star. Cut with care, I catch the light, what am I so hard and bright?

In a garden of colors, I stand tall and proud, dressed in royal hues. Often mistaken as a berry, I'm the nightshade's purple muse.

Some call me a walking dinosaur, but I'm actually a mammal. I'm also said to have inspired stories about unicorns, although I'm not the most elegant of all.

Endless blue cradle where sailors roam, Cradling life beneath my foam. I sing lullabies of whispers and gales, Carrying ships with my timeless tales.