A Heart in Horizon Zero Dawn is a small, organic item resembling a human heart but with subtle mechanical enhancements, reflecting the game's fusion of nature and technology. It has a smooth, slightly glossy surface with visible veins and arteries that glow faintly with a blue bioluminescent light, indicating its cybernetic enhancements. The heart is asymmetrical with a complex, organic shape, featuring small, intricate metallic plates embedded within the flesh, suggesting it's a hybrid of biological and robotic components.