Neodymium (neodytrium)

She left the lighthouse and went down to the beach to look at the moon pure and straight, and she stood in the shallows and let her feet sink into the sand as the patter-waves tickled her ankles. And that's when she saw it, a school of tiny fish, all darting around like marbles in a chalk circle, and they were lit up electric, mostly silver but some gold and pink too. They came and danced around her ankles, and she could feel their little electric fish bodies, and it was like she was standing under the moon and in the moon at the same time. And that was something she hadn't seen before.