A regular circle, hollowed out with rays and furrows, appears on a Japanese sandy background. Its diameter can reach about two meters. For a diver who discovers the structure without seeing its builder, the drawing looks more like a prepared work than the trace of a small animal.
The culprit, however, is a pufferfish, Torquigener albomaculosus. The male moves the sand with his fins and works for more than a week to compose this structure. The circles, reported by divers as early as 1995, intrigued before the behavior of their manufacturer was identified. Their function belongs to reproduction, not to a strange underwater message.
The construction serves to attract a female and spares a central area of fine sand. Its interest lies in this shift of scale: a relatively small fish shapes a relief that goes far beyond its own silhouette. The geometry remains spectacular, even when you remove the mystery added after the fact and just watch its fins move the grains.
What we know
Bridal construction of Torquigener albomaculosus, not of extraterrestrial origin.
To go to the source
References accessed October 11, 2026. Linked pages may be in another language.
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