Storm is a large lavender seahorse.
Storm is very loving to Mera and acts as her steed. He has the personality of a dog due to the way he holds the teddy bear in Mera's picture. Storm can be clumsy and funny sometimes.
In the first part of "Fish Out of Water", Mera talks to Storm about her struggles with fitting in at Super Hero High School until their conversation was interrupted when they heard Firefly chasing Miss Martian that night.
Storm also appeared in the second part of the episode when Mera rode him to create a gigantic wave and successfuly stopped Firefly. The next day, the students threw a pool party for Mera as a thanks for saving Miss Martian, and there she was reunited with Storm.
A younger version of Storm is also seen in the start of DC Super Hero Girls: Legends of Atlantis