Dark Blue Moon

Dark Blue Moon belongs to the impostor masquerading as Captain Tennille and appears in Stardust Crusaders. It is an aquatic humanoid resembling merfolk, sporting a flattened head, four eyes, a tall dorsal fin running down its back, extra fins along its legs, and webbing between its fingers and toes. Araki shaped it around ideas of raw vital strength fused with mineral matter, and it is drawn blue with red joints. The Stand stands in for the Moon tarot card, an emblem of trouble on the water, deceit, and dread of the unknown, fitting both its own nature and the way its user fools the Joestar group.

Dark Blue Moon is a creature of the sea, and its abilities sharpen dramatically in water while likely weakening on land. Its reach is long enough to strike Jotaro even with its user out of the water, and it is said to swim faster than any fish, quick enough to whip up a huge whirlpool just by spinning its webbed feet. Its user backs this up with remarkable lungs, holding his breath for as long as six minutes and twelve seconds so the fight can continue underwater. In the water the Stand's hands turn hard and razor-edged, sharp enough to wreck a spinning propeller or cut a shark clean in half.

It can also strip the sharp scales from its body and hurl them as blades, cutting Kakyoin's hand as he reaches into the water and drifting along the current to cut down anyone attempting to swim past. On top of that, it grows acorn barnacles that fasten onto a target, as they do to Star Platinum, sapping the victim's strength, granting the Stand a measure of control over the affected limbs, and letting it haul escaping foes back into the sea.

The false Captain Tennille is the sole user, an early enemy who conceals his identity aboard a ship and lures the Joestar group into a watery battle where Dark Blue Moon holds the advantage until Star Platinum destroys it.