Name: Petrodus patelliformis (dermal denticles)Age: CarboniferousLocation: Steeplehouse quarry, Wirksworth, Derbyshire, United Kingdom
I haven’t got around to separating or giving it my best shot to an i.d. on the associated crinoids as yet, but I thought you would like to see my work in progress.
If you would like to view the PDF below it makes for a very interesting read.
Steeplehouse quarry
p.s. the scale bar is in mm