| A large specimen of this classical trilobite from New York State. It assumed that Triarthrus eatoni had a symbiotic relationship sulfur bacteria. | |||
| Location: | Martinsburg, New York, USA | ||
| Size trilobite: | about 12 mm long | ||
| Age: | Upper Ordovizian, late Caradoc , (about. 449 Mill. Mill. y.o.) | ||