Coral, Marina's older sister in the animated series, possesses a bossy personality and a distinctive pink mermaid tail, marking her place within the underwater kingdom's royal merfolk family. She serves as part of the narrative's supporting cast.

In the episode "Sugar and Spice," exposure to Hedwig's magic potion transforms Coral into an infant. Held temporarily within the sea witch's lair, her infant state causes significant disruption, damaging the villains' environment extensively. The resulting chaos compels Hedwig to seek Marina's help to reverse the transformation.

Coral also appears in "Be Careful What You Wish For," interacting with an enchanted wishing well. Like others, her undisclosed wish undergoes an unexpected inversion due to the well's magic, contributing to the episode's broader magical complications affecting multiple characters.

Coral's experiences demonstrate recurring patterns of merfolk biology and magical vulnerability within the series' universe, aligning with established magical systems affecting both land and sea characters. No further canonical appearances, backstory expansions, or character development beyond these episodes are documented in official series media.