Frontispiece of Agostino Scilla's 'La Vana Speculazione', 1670 - note the variety of fossils on the lower right
Both Scilla and Steno arrived to conclusions that were beginning to shape the science of geology as it is known today, in particular the then-controversial notion that fossils are derived from once-living organisms.
Interestingly, some of the fossils which both chose to illustrate in their works were obtained from Malta. These fossils are the famous glossopetrae (tongue stones), or, more accurately, fossil shark teeth, which during the Medieval, Renaissance and Baroque periods were considered to be a miraculous cure for a variety of ailments (Zammit Maempel, 1975; 1989). Malta was the centre of a lucrative business in these shark teeth and it is not hard to see how specimens could have come in Scilla and Steno's possession.
Carcharocles megalodon (Agassiz, 1843) teeth from the C2 Phosphorite Conglomerate, Malta
Most of these glossopetrae belong to the extinct Carcharocles megalodon (Agassiz, 1843), one of the largest fish ever to exist on Earth. An approximation of its size (in grey and red) compared to the modern (and morphologically similar) great white shark, Carcharodon carcharias (L., 1758) (in green) can be seen below.
'St. Paul's Shipwreck', by Stefano Erardi, 1683 - note the snake falling out of the main figure's hands into the fire
Carcharocles teeth from the collection of Sir Hans Sloane are also the oldest Maltese fossils in the British Museum (cf. Galea Bonavia, 2003).
Galea Bonavia, C., 2003. Carcharocles megalodon (Agassiz) (Lamnidae: Neoselachae): A historical note. The Central Mediterranean Naturalist, 4 (1): 105.
Scilla, A., 1670. La vana speculazione disingannata dal senso: lettera responsiva circa i corpi marini, che petrificati si trovano in varii luoghi terrestri. Napoli: Colicchia.
Sloane, H., undated. Se la Virtu’ alessifarmaca della Terra, Glossopetre conchiti, Achini ed altre pietre figurate che si cavano dalle Rocche di Malta, sia innata o Miraculosa. Unpublished manuscript, Sloane Collection – British Library MS no. 763.
Zammit Maempel, G., 1975. Fossil sharks' teeth: a medieval safeguard against poisoning. Melita Historica, 6: 391-406.
Zammit Maempel, G., 1989. The Folklore of Maltese fossils. Papers in Mediterranean Social Studies, 1: 1-29.