Ghost Shrimp Dactyl (Claw Finger)
Callianassa sp. (cf. Callianassa californiensis or similar extant genera) • Body fossil; Invertebrate (Arthropod/Crustacean)
Geological Period
Cretaceous to Neogene (Commonly found in Pleistocene deposits)
Estimated Age
0.01 to 70 million years
Preservation Type
Recrystallization/Original Material. These specimens are often heavily calcified, retaining much of the original calcium carbonate structure, sometimes appearing 'sub-fossilized' if from more recent deposits.
Condition Assessment
Good. The specimen is an isolated element (dactyl) separated from the rest of the limb. Surface wear is moderate, likely due to water transport prior to burial.
Taxonomic Classification
Phylum: Arthropoda, Class: Malacostraca, Order: Decapoda, Family: Callianassidae (Ghost Shrimps)
Morphological Description
A calcified terminal segment of a crustacean cheliped (claw). Features a distinct curved dactylus (moveable finger) with a smooth, slightly translucent surface. Visible articulation point where it would join the propodus. Small punctations or pits are visible near the inner margin.
Rock Matrix
None adhering. Usually found in unconsolidated marine sands or soft mudstone layers.
Formation & Location
Common in the San Pedro Sand (California), the Calvert Formation (Maryland/Virginia), or similar coastal Cenozoic marine deposits worldwide.
Size & Dimensions
Approximately 1.5 cm - 2.5 cm in length; typical for a medium-to-large decapod of this genus.
Value & Rarity
Estimated Market Value
$5.00 - $15.00 USD
Auction Estimate
$10.00 - $20.00 (Usually sold in small groups or bulk lots)
Rarity Assessment
Common. Isolated claw fragments of ghost shrimp are frequent finds in Cenozoic coastal deposits.
Scientific Significance
Provides data on paleobathymetry and ancient shoreline positions. Callianassids are prolific burrowers; their presence indicates soft-bottom marine environments and helps map crustacean evolution and diversity.
Preparation Recommendations
Minimal preparation required. Gentle cleaning with soft brush and water. Store in a padded gem jar or small plastic container to prevent chipping of the brittle calcified edges.
Notable Features
Attractive creamy-yellow coloration and high degree of calcification giving it a 'bone-like' or 'ivory' appearance. The curvature and pointed tip are well-preserved.