Knobbed Starfish or Chocolate Chip Sea Star (Note: While commonly collected alongside shells, this is an echinoderm, not a mollusk)
Phylum: Echinodermata, Class: Asteroidea, Order: Valvatida, Family: Oreasteridae, Genus: Protoreaster, Species: Protoreaster nodosus · Oreasteridae (Cushion Star family) · Echinoderm (Starfish/Sea Star - calcareous endoskeleton rather than a true shell)
Species
Protoreaster nodosus
Shell Type
Echinoderm (Starfish/Sea Star - calcareous endoskeleton rather than a true shell)
Family
Oreasteridae (Cushion Star family)
Size
Approximately 6-8 inches across, which is average for an adult specimen of this species. Adults typically range from 5 to 11 inches in diameter.
Color & Pattern
Pale beige, tan, or light pinkish-brown base color featuring prominent, dark brown or black conical knobs (resembling chocolate chips) scattered along the upper surface and arms. The coloration is natural for a dried decorative specimen, though some fading from its original vibrant red or orange living state may have occurred.
Rarity
Common in its native range and widely available in commercial shell and curio shops, though collection from the wild is increasingly discouraged.
Habitat
Shallow tropical waters, typically found in intertidal to subtidal zones at depths ranging from 0 to 30 meters. Prefers sandy bottoms, seagrass beds, and coral rubble environments.
Geographic Range
Indo-West Pacific region, including the Red Sea, East Africa, Indian Ocean, Southeast Asia, Indonesia, and northern Australia.
Description
A striking and robust five-armed sea star covered in a dense array of small, bead-like granules across its aboral (upper) surface. The defining feature is the series of prominent, pointed conical tubercles or 'knobs' running down the center of each arm and around the central disc. The texture is rough and calcified, typical of dried echinoderm skeletons.
Key Features
Distinctive dark brown conical knobs (tubercles) contrasting against a lighter granular background, five relatively broad and bluntly pointed arms, and a heavily granulated dorsal surface.
Collector Value
Low to moderate commercial value. While popular as a decorative coastal item or entry-level specimen for casual beachcombers, it holds limited value for serious conchologists since it is not a mollusk. Sells typically for a few dollars.
Condition Notes
Dry specimen in good, stable condition. Intact arms with minor natural wear on the granular surface. Common for decorative dried specimens, lacking the soft tissue and tube feet of a live animal.
Interesting Facts
Despite being frequently sold alongside seashells in gift shops, sea stars are not mollusks but echinoderms, closely related to sea urchins and sea cucumbers. They use a water vascular system and hundreds of tiny tube feet for locomotion and capturing prey.
Ecological Role
Acts as an opportunistic scavenger and carnivore, feeding on sponges, detritus, and small benthic invertebrates. Helps maintain benthic community balance, though over-collection for the curio trade poses local conservation concerns.
Similar Species
Protoreaster linckii (Red-knobbed starfish), which features brighter red knobs and a more reddish-orange reticulated network on a whitish background.
Beach Finding Tips
In its native Indo-Pacific range, live individuals can sometimes be spotted in very shallow seagrass flats during extreme low tides. However, taking live sea stars is harmful to local populations and often illegal in protected marine reserves.