Ichthyolith
An ichthyolith, meaning "fish", and λίθος is any disarticulated remains of a fish found in the fossil record, most often a scale, denticle or tooth. Ichthyoliths are found in nearly all marine sediment.
The term was coined by Doyle, Kennedy and Riedel to denote 'fish skeletal debris'.
The term 'stratignathy', proposed in the same paper for the time relationships of ichthyoliths, did not gain currency.