Foraminifera Used In the Construction of Miocene Polychaete Tubes, Monterey Formation, California, USA
The foraminifera make up tubes similar to those constructed by some modern marine worms. Because agglutinated worm tubes readily disaggregate after the worm's death, very few of them have been found in the fossil record. And although some modern worms construct their tubes with foraminiferal tests, the fossil record of this phenomenon to date is represented by a single specimen from the Lower Jurassic. The fossil tubes from California have closest affinity with the genus Pectinaria, which includes Recent species living at littoral to abyssal depths. Foraminiferal tests were likely the most predominant sand-sized particles available to the worm in these particular environments; the worm did not purposefully select foraminiferal tests. Disaerobia may then have enhanced the chances of tube preservation, but subsequent leaching at the Carmel localities removed most calcareous test material from the sediment.