Fossilized Burrow Cast / Ichnofossil
cf. Thalassinoides or Ophiomorpha ichnosp. • Trace fossil (Ichnofossil) and sediment-filled burrow cast
Geological Period
Quaternary to Neogene
Estimated Age
2 to 23 million years
Preservation Type
Permineralization and sediment infilling with secondary iron oxide (limonite/goethite) staining
Condition Assessment
Good. The specimen is an incomplete fragment of a larger burrow system, displaying stable consolidated matrix and clear internal structural cavity without active crumbling.
Taxonomic Classification
Ichnogenus: cf. Ophiomorpha or Thalassinoides (produced by decapod crustaceans such as ghost shrimp or lobsters)
Morphological Description
Cylindrical to irregular tubular structure featuring a hollowed or hollow-centered chamber filled with internal sediment and secondary mineral deposits. The outer surface is rough and undulating, showing burrow wall linings and textural variations from churning bioturbation.
Rock Matrix
Iron-stained sandstone and sandy mudstone matrix with quartz grains and secondary iron oxide cementation
Formation & Location
Coastal, shallow marine, and estuarine deposits worldwide, commonly found in formations like the Calvert Formation (USA) or similar marginal marine strata
Size & Dimensions
Approximately 4 cm in length and 2.5 cm in width, typical for invertebrate crustacean burrows of this type
Value & Rarity
Estimated Market Value
$15 - $40
Auction Estimate
$10 - $30
Rarity Assessment
Common
Scientific Significance
Provides critical paleoecological evidence of ancient benthic invertebrate behavior, substrate consistency, oxygenation levels, and bioturbation rates in shallow marine paleoenvironments.
Preparation Recommendations
Gentle mechanical cleaning with a soft brush to remove loose surface dirt. Stabilization with a dilute polyvinyl butyral (PVB) or Paraloid B-72 consolidant if matrix is friable. Store in a dry environment.
Notable Features
Distinct hollow interior cavity lined with a distinct contrasting mineralized crust, showing the classic internal structure of a crustacean dwelling or feeding burrow.