Scary Monster

Scary Monster (スケアリー・モンスター) is a Stand-like ability gained by Diego Brando in Part VII: Steel Ball Run.

This ability seems to be derived from the effects on Diego of Dr. Ferdinand's Stand, Scary Monsters; retained by Diego with the power of the Corpse's Left Eye.

Appearance
Transforming into the dinosaur Deinonychus; Diego gains stripes spelling out "DIO" all over his body. His hair turns into spikes that end in round, ball-shaped tips on the back of his head. Traces of his checkered shirt are still visible on his chest.

After being under the influence of the Stand for a while, Diego is able to turn into a more human-shaped form while still retaining sharp teeth, claws, dinosaur legs and a tail, with a deranged, mad expression on his face.

As the Stand is bound to Diego's body, its appearance is based on the form he takes.

Abilities
Morph: Diego is capable of changing his body from that of a human to that of a half-dinosaur, fully fledged or partial form of it. While in his morph status he has an increased stamina, strength, speed and vision along with being capable of eating anything. It far surpasses human limits, but without the weakness to sunlight.

Transmute: Diego can morph other creatures into dinosaurs as well, an ability retained from the original Scary Monsters. Diego typically uses this ability to create armies of miniature carnivorous raptors out of birds, rats or fleas, or turn his own horse into one to grant it the ability to climb walls.

Fossilize: Introduced later in the story, Diego demonstrates the ability to not only turn other beings into dinosaurs but, if he wishes to do so, alter them into a hardened dormant state much like a fossil. The ability can be used a variety of ways, from fusing a being into a structure like a rock or tree as a camouflage (not unlike the dormant state of the Pillar Men) to shaping the fossilized being into something more creative like candle holders.

Hand to Hand: Perhaps the most curious and unique ability of Dio's power. Being bound to his body, Scary Monster allows him to fight in first person against other Stands and physically damage them, whereas normally Stands can be damaged only by other Stands.

Senses: In this form, Diego also possesses the ability to view things in high speed, enabling him to dodge attacks and predict the other horses' actions.

History
While Scary Monster acts like a Stand, it is debatable on whether or not it is considered a "true" Stand and not just the lingering effect of the stand Scary Monsters permenantly fusing to Diego after obtaining the Turbo Eye.