The heart of a glass shell.

She grabbed a handful of dirt, and in the middle placed a pinch of sand from the beach.
Then, placed the handful of dirt into a drawer used as a planting bed. After three nights of moonlight and morning dew, a shell started to emerge and grow from the drawer. She moved it inside, as it needed a lot more care and to be held backwards underwater for another three nights.
In the fish tank where she placed the drawer, the dirt didn't fall to the bottom; it held steady as the shell grew bigger.
At midnight on the last day, she pulled the drawer through the glass of the fish tank. The drawer opened like it was part of the glass and from it, she plucked the shell.
Carefully holding it she put it up to the light, watching how the rays of light changed as they went through it. The shell was made of glass and inside it was the last ingredient that she could see moving and palpitating inside the shell.
She grabbed a thin ice breaker and a small rubber hammer and placed the shell on a counter. With goggles on, she pulled down the face shield part of a welding helmet and with shaky hands started to pry the shell open.
One hit after the other, she started to separate both sides of the shell making an opening big enough for a finger. After that, she used both hands and used all her force to slowly open the shell. Fully open, and sitting on the countertop she grabbed the center of the shell with a pair of pliers.
It was a red and orange orb with colors flowing inside of it without mixing. Carefully with arms fully extended to not get too close but focusing completely not to drop it, she put it inside a glass container.
Lifting the face shield and wiping sweat off her forehead she brought out a cauldron where the rest of the potion was. "The first wish upon a star in the last light of daylight branded in the sand" she read through the goggles from the dusty book as she dropped the orb into the cauldron.