Red Pencil Sea Urchin Heterocentrotus Mammillatus

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Red Pencil Sea Urchin – Heterocentrotus mammillatus

Overview:
The Red Pencil Sea Urchin is a striking and unique urchin, instantly recognizable by its thick, bright red spines resembling pencils. More ornamental than functional, it adds a bold splash of color and texture to aquariums.

Origin:
Native to the Indo-Pacific, often found in rocky reef areas exposed to strong surge zones.

Feeding:

• Feeds on algae, biofilm, and detritus.

• Supplement diet with dried seaweed, algae wafers, or fresh macroalgae if natural algae growth is limited.

Tank Mates:

• Reef-safe, but its size and strength mean it can dislodge corals or rockwork.

• Avoid with predatory fish such as puffers and triggers.

Aggression Level:
Peaceful. Will not bother tank mates but may inadvertently shift décor while moving.

Experience Level:
Intermediate. Requires stable, well-established aquariums with ample algae and strong rockwork.

Water Parameters:

• Temperature: 72–78°F (22–26°C)

• pH: 8.1–8.4

• Salinity: 1.023–1.025

• Tank Size: 75+ gallons

Unique Features:

• Iconic thick red spines for a dramatic display.

• Long-lived and hardy in stable reef systems.

• Excellent at helping control algae, though slower than other urchins.

✨ The Red Pencil Sea Urchin is both a conversation piece and functional grazer, perfect for large, established reef tanks.

Above images for illustration purposes only. Exact colours, patterns, and size may vary between individuals.

Please note: The livestock that is sold on our online site is not held in store at our Swell shop, or available for collection from the shop. Species sold at our Swell store will differ from ones available to order to your door.

All livestock deliveries are subject to our full Delivery Terms & Conditions, please read before ordering.