In this 2005 story from MacArthur winner Karen Russell, two brothers search for the ghost of their drowned sister.
"Olivia disappeared on a new-moon night. It was exactly two years, or twenty-four new moons, ago. Wallow says that means that tonight is Olivia’s unbirthday, the anniversary of her death. It’s weird: our grief is cyclical, synched with the lunar cycles. It accordions out as the moon slivers away. On new-moon nights, it rises with the tide."