Green Sea Urchin Test (also known as the Sea Egg)
Kingdom: Animalia, Phylum: Echinodermata, Class: Echinoidea, Order: Camarodonta, Family: Parechinidae, Genus: Psammechinus, Species: Psammechinus miliaris · Parechinidae (Sea Urchin family) · Echinoid Test (not a true mollusk shell). Shape: Globular/Spherical with a flattened base.
Species
Psammechinus miliaris (confidently identified based on globular shape and olive-green pore-pair arrangement)
Shell Type
Echinoid Test (not a true mollusk shell). Shape: Globular/Spherical with a flattened base.
Family
Parechinidae (Sea Urchin family)
Size
Approximately 1.5 to 2 inches (3.5 - 5 cm) in diameter. This is a mature adult size for this species.
Color & Pattern
Mottled olive green and creamy white base. Features five distinct ambulacral segments with vertical rows of light-colored primary tubercles. Colors are natural and well-preserved.
Rarity
Common (frequently found washed up after storms or in tide pools along European coastlines).
Habitat
Coastal marine environments; typically found in the intertidal and shallow subtidal zones among rocky shores, seagrass beds, and oyster banks.
Geographic Range
Eastern Atlantic Ocean, ranging from Scandinavia and the North Sea down to Morocco and the Mediterranean.
Description
An attractive, radially symmetrical endoskeleton known as a 'test.' It features a complex pattern of raised bumps (tubercles) where spines once attached. The test is divided into ten sections (ambulacral and interambulacral areas) that converge at the apical system on top.
Key Features
Pentamerous (five-part) symmetry; small, closely packed tubercles; greenish-brown coloration with white highlights; circular peristome (mouth) opening on the bottom.
Collector Value
Minimal to moderate ($2 - $10). They are more valued for their aesthetic and educational appeal than monetary value, unless found in pristine, 'gem' condition with spines still attached.
Condition Notes
Fair to Good. The test is mostly intact with good color retention, though the apical plates are missing (the hole at the top), and there is slight wear on some tubercles. Collectibility: Fine.
Interesting Facts
Unlike mollusks, urchins use 'water vascular systems' to move. In life, they are covered in sharp spines and tube feet. This species often 'decorates' itself by holding shells or seaweed over its body with its tube feet for camouflage.
Ecological Role
High significance as a grazer (algae control). They are a vital food source for sea otters, crabs, and large fish. Not currently listed as endangered.
Similar Species
Echinus esculentus (much larger and usually pink/red), Strongylocentrotus droebachiensis (larger and more uniform green).
Beach Finding Tips
Look in the high-tide drift line after a heavy storm or search inside crevices in rocky tide pools. Handle carefully as the tests are very fragile once the animal dies and the organic matter decays.