Dark Blue Moon is a humanoid Stand with aquatic features. It manifests itself as some sort of merfolk-like entity with a flat head, four eyes, a large dorsal fin lining most of its back, additional fins on its legs, and webbed hands and feet.
According to JOJOVELLER, his form was made while thinking of a combination of vital strength and of mineral material.
Dark Blue Moon represents the Tarot Card The Moon, which symbolizes trouble in water, lies, betrayal and fear of the unknown.
Dark Blue Moon is a marine Stand, and as such, his skills are more effective in an aquatic environment. It is probably less effective in a terrestrial environment, but this is unknown.
Dark Blue Moon has a high enough range that it was able to attack Jotaro without the user even being in the water. Its user has stated that it swims faster than any fish in the sea, a trait proven to be true when Dark Blue Moon manages to create a giant whirlpool by simply spinning its webbed feet fast enough.
Its Stand user also had an incredible lung capacity, being able to hold his breath for up to a personal record of six minutes and twelve seconds, which helped the Stand to maintain a battle even if the user was thrown inside water (Most people would be unable to battle and keep himself/herself from not drowning at the same time, as shown with Rubber Soul).
- Razor Scales: Dark Blue Moon's scales can also act as razors. Because of their sharpness, they are strong enough to destroy a still running engine propeller and slice a shark in two with ease. The Stand can also use them as projectiles, throwing them against the enemy.
- Barnacles: It is also capable of creating barnacles, specifically acorn barnacles, as seen when they attach to Star Platinum soon after making contact with Dark Blue Moon's skin. The barnacles drain the target of its strength, but also allow Dark Blue Moon slight control over the infected body parts, allowing it to drag foes back into the water if they try to escape. This, combined with its natural aquatic characteristics, makes Dark Blue Moon a deadly opponent.