Common Paper Bubble, Paper Bubble Shell
Phylum: Mollusca, Class: Gastropoda, Order: Heterobranchia, Family: Aplustridae, Genus: Hydatina, Species: Hydatina physis · Aplustridae (Bubble Snail family) · Gastropod univalve, whole shell, fragile spiral shape
Species
Hydatina physis
Shell Type
Gastropod univalve, whole shell, fragile spiral shape
Family
Aplustridae (Bubble Snail family)
Size
Approximately 1 inch in length and width, which is average for this species. Adults typically range from 0.75 to 2 inches.
Color & Pattern
Translucent to pale whitish base with delicate, thin brown spiral bands. The surface is glossy, smooth, and paper-thin, revealing the internal structure of the shell.
Rarity
Uncommon to Rare as a complete, undamaged beach find due to the extreme fragility of the shell.
Habitat
Shallow subtidal zones, intertidal pools, coral rubble, and sandy or muddy flats in tropical and subtropical marine environments.
Geographic Range
Indo-Pacific region, spanning from the Red Sea and East Africa across to Polynesia, including the waters of Australia and Japan.
Description
An exquisite and remarkably fragile shell characterized by its inflated, globular, bubble-like shape. The shell is thin and translucent, featuring fine spiral lines across a glossy exterior with no distinct spire. The large aperture is wide and open, running the entire length of the shell.
Key Features
Extremely thin, paper-like texture; inflated bubble shape; lack of a prominent spire; translucent appearance with delicate spiral banding.
Collector Value
Moderately sought after by specialist shell collectors who appreciate delicate and unusual forms. Value is generally low to moderate due to small size, but pristine specimens with intact lips command higher interest.
Condition Notes
Intact whole shell in good condition given the inherent fragility of the species. Minor wear along the outer lip, but retains its structural integrity and glossy luster. Collectibility grade is Fine.
Interesting Facts
The living animal is a colorful sea slug with a large, ruffled mantle and bright pinkish-purple margins. They are carnivorous hunters specializing in feeding on filamentous green algae and terrestrial-like flatworms.
Ecological Role
Functions as a low-level predator and grazer in shallow marine food webs, helping control algae populations on coral reefs and sand flats.
Similar Species
Bullina lineata (Striped Bubble), which features more distinct dashed lines rather than smooth solid spiral bands.
Beach Finding Tips
Look in calm, protected bays, lagoons, and reef flats after gentle tides. Because of their fragile nature, they are rarely found intact on high-energy surf beaches; sift carefully through fine shell drift.