Mendeleev's predicted elements
Dmitri Mendeleev published a periodic table of the chemical elements in 1869 based on properties that appeared with some regularity as he laid out the elements from lightest to heaviest. When Mendeleev proposed his periodic table, he noted gaps in the table and predicted that as-then-unknown elements existed with properties appropriate to fill those gaps. He named them eka-boron, eka-aluminium and eka-silicon with atomic masses 44, 68 and 72 respectively.
Dispilio Tablet
The Dispilio tablet is a wooden tablet bearing inscribed markings, unearthed during George Hourmouziadis's excavations of Dispilio in Greece, and carbon 14-dated to 5202 (± 123) BC. It was discovered in 1993 in a Neolithic lakeshore settlement that occupied an artificial island near the modern village of Dispilio on Lake Kastoria in Kastoria, Western Macedonia, Greece.