Mareanie is usually found moving along the ocean floor near coastal areas. The spike on top of its head contains a deadly toxin that is injected into prey. Mareanie is also able to finish off its weakened victim with all ten of its tentacles.
Sometimes when a wild Corsola calls for help in an SOS battle a Mareanie appears instead. When this happens, the Mareanie attacks Corsola first before targeting the player's Pokémon.
This is similar to Carbink, as Sableye may appear instead when calling for SOS. Similarly to Mareanie, the Sableye will attack the Carbink first, then the player.
Mareanie may be based on a sea urchin mixed with a Crown-of-Thorns starfish. Its predation of Corsola may be based on how Crown-of-Thorns starfish destroy coral reefs by feasting on the growing polyps.
Mareanie comes from "marine", "meanie", and possibly "echinoderm". Parts of its name may also be taken from "sea anemone".
Names in other languages
Japanese: ヒドイデ Hidoide (mixture of 酷い hidoi (cruel) and 海星 hitode (sea star)).
Korean: 시마사리 Simasari (mixture of 심하다 simhada (severe) and 불가사리 bulgasari (sea star)).
French: Vorastérie (mixture of vorace (voracious) and astérie (sea star)).
German: Garstella (mixture of garstig (nasty) and Stella Marina (Latin for sea star)).