In heraldry, the nautilus is an unusual but elegant marine charge associated with wisdom, proportion, mystery, exploration, and the hidden order of nature. Its spiral shell gives it a powerful visual and symbolic character. The spiral can suggest growth, continuity, mathematical harmony, unfolding knowledge, and the journey inward or outward. As a sea creature, the nautilus also carries meanings of navigation, depth, adaptability, and life shaped by the ocean. In a coat of arms, it is especially suited to armigers connected with science, natural history, maritime trade, coastal places, or intellectual discovery.

The nautilus belongs to a wider heraldic tradition of shells, sea creatures, and marine emblems. While scallop shells are far more common in medieval heraldry, especially as signs of pilgrimage and Saint James, the nautilus has become more appealing in modern heraldry because of its scientific and aesthetic associations. Its chambered shell may represent accumulated experience, ordered development, and protection through structure. In institutional arms, it can point to marine biology, museums, universities, oceanography, mathematics, or conservation. In civic arms, it may suggest a coastal economy, island identity, or seafaring heritage.

Specific historic examples of nautilus shells in formal armory are less common than ships, dolphins, anchors, or scallops, but the charge is readily understandable when clearly blazoned and depicted. It may appear as a shell, a living nautilus, or a spiral form, often argent, or proper, and combined with waves, stars, compasses, books, or anchors. Related maritime charges can be explored through Heraldry of the World, with broader principles from The Heraldry Society and the College of Arms. In coats of arms, the nautilus offers a refined emblem of oceanic knowledge, natural design, continuity, and thoughtful exploration.