A lit curve teases. A thin arc of sunlit lunar terrain, suspended against a dark field, reaches the eye as a stripped-down signal; yet the visual system dislikes leaving such a signal unfinished, so it supplies a shape with appetite, comedy, and the hint of a bedtime tale. The Moon has not changed.
The error is useful. Pareidolia, the tendency to find meaningful forms in ambiguous input, recruits top-down processing: expectations from memory help the visual cortex interpret incomplete contours before deliberate thought catches up. The curve wins quickly. A banana offers an economical match because its silhouette is simple, its bend is pronounced, and its cultural presence is common; the mind selects resemblance, not astronomy. Under Gestalt grouping, the lit crescent reads as one bounded figure even though it is merely the portion of the lunar disk illuminated from the viewer's angle. Physics stays plain.
A useful mistake. It turns orbital geometry into a private picture-book prop, while preserving a strange truth: the same brain that can infer depth, edges, and motion from sparse evidence is also ready to snack on a curve. No lesson required. The crescent remains rock, shadow, and reflected sunlight; still, above rooftops or bare branches, it can carry the comic weight of fruit. There, perception shows its old bargain, speed for certainty, and leaves a bright hook hanging in the dark.