Some enemies in
Phantasy Star can be found only on or near bodies of water, such as lakes or oceans. These tend to be themed as sea life, such as the Shellfish and close relative, Ammonite. This pair returns to plague Alis and her companions in
Phantasy Star - Deluxe Edition. They have changed somewhat, trading the opening shell from which they spat a droplet of water for tentacle-like protrusions we see here. In the game's internal references, this coloration is called Ammonite, even though it more closely resembles the Shellfish variant in the original game.