The Pet Giant Wisp is a luminous, ethereal creature with a spherical core that glows with a soft, pulsating light, reminiscent of will-o'-the-wisps found in mystical forests. Its form is semi-transparent, with wispy tendrils extending outward, giving it a ghostly appearance. The core's color varies from pale blue to vibrant green, depending on the time of day or the wisp's mood. The surface of the wisp is smooth and slightly reflective, with a subtle iridescence that catches the light as it moves. The tendrils are delicate and flow gracefully, adding to the creature's otherworldly charm.