Attempts to decipher the inscriptions produced no results, and establishing the slab's approximate age proved to be quite a problem. Radiological and chemical methods were used, but they produced no conclusive result. Two shells were found on the slab's surface. The age of one of them - a Navicopsina munitus of the Gyrodeidae family - is 50 million years. The other (Ecculiomphalus princeps of the Ecculiomphalinae family) is 120 million years old. Scientists assume the second is the correct age. Dr. Chuvyrov says the map might have been created at the time when the earth's magnetic pole was in what is now Franz-Joseph Land, which means roughly 120 million years ago. Original estimates put the slab's age at 3,000 years, but when the shells encrusted into the map were found, it was assumed that the slab was much, much older.