Pencil Sea Urchin (Algae Eater)

Macroalgae Farms

Pencil Sea Urchin (Algae Eater)

$19.79 $21.99
-10%

Key Features:
⭐ Distinctive pincushion silhouette with thick, blunt spines — unlike any other reef invertebrate
• Active algae grazer — eats hair algae, film algae, diatoms, and overgrown coralline
• Blunt, non-venomous spines make this one of the safer urchin species to keep
• Hardy, peaceful, and reef-safe with corals and other invertebrates

In stock

This product will be available for sale in 2 weeks, but you can pre-order now to receive 10% discount!

Estimated delivery between September 06 and September 08.

Pencil Sea Urchin (Algae Eater)
$19.79 $21.99
$19.79 $21.99

About this item

Pencil Sea Urchin (Algae Eater)

Note: This is a general description of the species — the specific specimen you receive may vary in color, size, and appearance.

The Pencil Sea Urchin (Eucidaris sp. / Heterocentrotus sp.) is one of the most functional, distinctive, and reef-safe algae grazers available in the entire saltwater hobby. Thick, blunt spines radiate from a spherical body in colors ranging from cream and reddish-brown to vibrant red-orange, giving the pencil urchin an unmistakable silhouette that is completely unlike any other invertebrate in the reef trade — the classic "pincushion" profile that has made this species a favorite among reefers looking for something visually different alongside its genuine utility. Slow-moving and completely peaceful with tankmates, pencil urchins bring both functional algae control and a distinctive sculptural presence to any established display.

What makes the Pencil Sea Urchin one of the most valuable invertebrate additions to any established reef is its active algae-grazing behavior. Pencil urchins are one of the most effective natural algae grazers available to reefers — actively consuming hair algae, film algae, diatoms, and overgrown coralline algae that other cleanup crew invertebrates leave untouched. Unlike more dangerous urchin species (Diadema long-spined urchins), pencil urchin spines are blunt and non-venomous, making them safe to handle carefully and reef-safe with corals and other invertebrates. Hardy, adaptable, and long-lived, the pencil urchin is one of the best all-around functional invertebrates a reef keeper can add.

Available Options

Full Starter Plant

One healthy Pencil Sea Urchin — exact color and species selected from current availability. Thick, blunt spines with distinctive pincushion silhouette. Ready to acclimate, explore, and begin grazing algae from day one.

Care Information

Temperature 72–78°F (22–26°C)
Salinity 1.023–1.026 — stable parameters recommended
Tank Size 30 gallon minimum — established reef with rockwork and grazing surfaces
Diet Herbivore — hair algae, film algae, diatoms, coralline algae
Temperament Peaceful — reef-safe with corals and invertebrates
Care Level Easy — hardy and beginner-friendly

Special Considerations

Pencil Sea Urchins are physically slow-moving grazers that can occasionally knock over unsecured frags, small rockwork, or loose decorations as they navigate the aquascape. Secure all frag plugs and small rocks with reef-safe glue or aquascape putty to prevent accidental displacement. Pencil urchins actively graze coralline algae as part of their diet — this is beneficial for controlling overgrown coralline on glass or unwanted surfaces, but reefers who value heavy coralline growth on rockwork may see gradual reduction in coralline coverage over time. Most pencil urchin species are more active at night; expect the urchin to hide during the day and emerge to graze after lights out — this is completely normal behavior. Pencil urchins are safe to handle carefully, but the blunt spines can still cause minor scrapes if handled roughly. Avoid copper-based medications, which are fatal to sea urchins and other invertebrates. Provide stable salinity and gradual acclimation over 60–90 minutes on arrival, as urchins are sensitive to sudden parameter changes.

🔍 Aquarium Insights

The Pencil Sea Urchin is one of the most useful and visually distinctive invertebrates in the reef hobby:

  • Active algae grazer — actively consumes hair algae, film algae, diatoms, and overgrown coralline
  • Blunt, non-venomous spines — safer to handle than long-spined urchin species
  • A hardy, peaceful invertebrate that combines striking sculptural presence with genuine biological pest control — beautiful and functional in equal measure

Learn More

For detailed species information, compatibility, and care tips, visit our Species Library.

Livestock Disclaimer

Due to natural variation, the Pencil Sea Urchin you receive will be selected based on current availability and may range across species (Caribbean pencil urchin or Indo-Pacific slate pencil urchin) and color expressions including cream, reddish-brown, red-orange, and brick red. Specific species and color cannot be guaranteed and are determined at packing time.

Photographs are representative examples. Individual specimens may vary in size, spine length, and color intensity.

As with all live animals, proper acclimation and a stable, established environment are essential for best results.

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