Heart Urchin – Maretia planulata

Common name: Heart Urchin
Scientific name: Maretia planulata
Origin: Indo-Pacific
Adult size: 6–10 cm
Temperament: Peaceful
Diet: Detritivore
Minimum tank size: 200 L+ (mature sand bed)
Reef safe: Yes

Overview

Maretia planulata is a sand-burrowing heart urchin known for its oval, heart-shaped body and soft spines. Unlike rock-grazing urchins, this species lives within the sand bed, where it plays an important role in substrate maintenance and natural aeration.

Best suited for mature reef aquariums with established sand beds.

Behavior & Sand Requirements

Peaceful and completely reef safe.

Requires:
• Deep, fine sand bed
• Large open sand area
• Mature system with natural microfauna

Spends most of its time buried beneath the substrate, moving slowly while feeding.

Feeding

Primarily consumes:
• Detritus
• Organic matter within the sand
• Microfauna

Because it feeds within the substrate, supplemental feeding is difficult. It depends on a naturally rich and established sand bed.

Care Notes

• Sensitive to sudden salinity or parameter changes
• Does not tolerate copper-based medications
• Not suitable for bare-bottom aquariums
• May slowly starve in new or very clean systems

A specialized sand-dwelling echinoderm best suited for large, mature reef aquariums with deep and biologically active substrate.