Mortensen's Heart Urchin test or fragment, often referred to as sea biscuit or irregular sea urchin test
Phylum Echinodermata, Class Echinoidea, Order Spatangoida, Family Loveniidae, Genus Meoma, Species Meoma ventricosa · Loveniidae (Heart urchin family) · Echinoid test (not technically a mollusk shell, but calcareous exoskeleton of an echinoderm), fan/dome shape fragment
Species
Meoma ventricosa or related spatangoid echinoid (High confidence for irregular echinoid test fragment)
Shell Type
Echinoid test (not technically a mollusk shell, but calcareous exoskeleton of an echinoderm), fan/dome shape fragment
Family
Loveniidae (Heart urchin family)
Size
Approximately 2-3 inches across based on visible proportions, typical of mature Gulf of Mexico spatangoid urchins which range from 2 to 5 inches.
Color & Pattern
Pale tan to sandy beige with a weathered appearance. Prominent raised ambulacral grooves and tubercle patterns showing natural calcareous composition, heavily sun-bleached.
Rarity
Common to Uncommon as beach fragments, though finding a whole, intact test is an exciting find for beachcombers.
Habitat
Burrowing in soft marine substrates such as fine sand, mud, or seagrass beds in shallow to moderately deep sub-tidal waters.
Geographic Range
Western Atlantic, Caribbean Sea, and the Gulf of Mexico, including the Texas coast where it washes ashore post-mortem.
Description
A fragile calcareous test fragment featuring distinctive parallel rows of tubercles and ambulacral grooves characteristic of irregular sea urchins. The structure displays intricate porous patterns where spines once attached, presenting a tactile, ridged texture.
Key Features
Distinctive symmetrical rows of pores and tubercles arranged in petaloid patterns on the aboral surface, characteristic of burrowing heart urchins.
Collector Value
Low commercial value, but highly prized by amateur beachcombers and shell collectors as a unique addition representing marine echinoderms rather than mollusks.
Condition Notes
Weathered fragment with missing sections and worn edges. Moderate sun-bleaching and erosion from wave action. Graded as Fair to Good for a beach-cast echinoid fragment.
Interesting Facts
Unlike regular sea urchins, heart urchins are bilaterally symmetrical and adapted for burrowing deep beneath the sand, using specialized spines to maintain a respiratory chimney.
Ecological Role
Heart urchins act as important bioturbators, churning up sediment to oxygenate the sea floor and recycling organic material in benthic ecosystems.
Similar Species
Other irregular echinoids such as sand dollars (Clypeasteroida) or other heart urchin species like Plagiobrissus grandis, distinguished by pore arrangement and overall test shape.
Beach Finding Tips
Look along high-tide drift lines on sandy Gulf Coast beaches following storms or rough surf, where lightweight calcareous tests and fragments are deposited.
Notes
Surfside Beach Texas