Molluscs · Turbinidae
Astralium calcar
Spurred turban
Small star-shaped turban from the Indo-Pacific, sold among others as "Ninja star snail". Its flattened shell, edged with a crown of spines, grazes algae and biofilm. Note: the name "Ninja star" also covers other species depending on the seller.
- intermediate level
- Adult size
- ≤ 6 cm
This sheet is still being written. Some sections are not filled in yet: they stay hidden while they are empty.
What it needs
Water parameters
- Temperature°C
- SalinitySG
- pH
Day to day
Care and feeding
- LevelIntermediate
- FoodHerbivore
Care
Level: sellers disagree. Quality Marine rates it "Easy", Aquarium Depot "Moderate"; this card uses intermediate, to be safe.
Acclimation: no species-specific instructions found; go slowly, as for any invertebrate, and never use copper (Quality Marine).
Setup: rock to graze; Quality Marine lists reef and sand flats as habitat, and the genus also lives in seagrass beds.
Tankmates: peaceful (Aquarium Depot), "social" for Quality Marine. None of the sources consulted explicitly calls it reef compatible; it is a herbivorous grazer, but watch it around your corals.
Watch point: many star-shaped trade snails struggle to right themselves once on their back (LiveAquaria for its "Ninja star"); no source was found for A. calcar itself, but keep an eye on it.
Feeding
Herbivore: it feeds mainly on algae and biofilm (Aquarium Depot); Quality Marine adds detritus for the genus Astralium, which helps keep algae in check in its habitat.
None of the sources consulted gives a supplement specific to this species; for grazing snails in general, Quality Marine recommends dried algae or vegetable pellets when algae run short.
Decor
- Algae-covered rock to graze.
- Open sand area (habitat "reef, sand flat" per Quality Marine).
Tank mates
Compatibility
Goes well with
- Peaceful fish and invertebrates.
- Burrowing snails (Nassarius, Cerithium): complementary roles.
Avoid
- Copper treatments: lethal.
- Tank without algae: it starves.
In detail
Description
Identification: more or less depressed conical shell, about 2.8 cm high and 4 cm across (up to 6 cm), greyish green or ashy brown; six whorls flattened above, folded; the periphery is keeled and bears about twelve radiating spines on the body whorl. The aperture is oval and oblique, golden inside, the columella stained purple or blue. Synonyms: Astraea calcar, Turbo calcar.
Confusions: Aquarium Depot sells Astralium calcar as "Ninja Star Snail", but LiveAquaria sells its "Spiny Star Astraea (Ninja Star Snail)" as Astraea phoebia; Quality Marine sells A. calcar as "Spurred Turban" and says it is not often seen in the trade. Check the scientific name when buying.
In the wild it lives on rocky shores and in shallow water (3 to 12 m), from the Andaman Sea to Melanesia, from southern Japan to New Caledonia, and as far as Queensland. No data was found on breeding in aquariums.
Characteristics
- Flattened star-shaped shell, about 4 cm across (up to 6 cm).
- About twelve spines on the body whorl; golden aperture, purple or blue columella.
- Sold as "Ninja star" (Aquarium Depot) or "Spurred turban" (Quality Marine).
- Grazes algae and biofilm.
- Not often seen in the trade according to Quality Marine.
- Indo-West Pacific, rocky shores and shallow water (3 to 12 m).
Origin
- Indo-West Pacific
Distribution
- From the Andaman Sea to Melanesia, from southern Japan to New Caledonia; Philippines, Indo-Malaysia, Queensland
- Rocky shores and shallow water, 3 to 12 m
Status
Conservation
Not evaluated (NE)
WoRMS
Classification
- Kingdom
- Animalia
- Phylum
- Mollusca
- Class
- Gastropoda
- Order
- Trochida
- Family
- Turbinidae
- Genus
- Astralium
- Species
Where this comes from
Sources
- WoRMSWoRMS — Astralium calcar (Linnaeus, 1758) (AphiaID 413386) (opens in a new tab) · accessed on November 11, 2026
- WebSeaLifeBase — Astralium calcar, Spurred turban (species summary) (opens in a new tab) · accessed on November 11, 2026
- WebWikipedia (en) — Astralium calcar (opens in a new tab) · accessed on November 11, 2026
- WebQuality Marine — Spurred Turban Snail (Astralium calcar) (description and care info) (opens in a new tab) · accessed on November 11, 2026
- Web
Related species
Other molluscs
West Indian starsnail
Lithopoma tectum