Alas, dear Apple, you are at least 2000 years too late in your design claim for "thin" writing tablets. You were preceded by the "wafer thin" Vindolanda wooden tablets, which are dated to the 1st and 2nd centuries AD.
As written at the British Museum and at Wikipedia, quoting the Wikipedia:
"The Vindolanda tablets are "the oldest surviving handwritten documents in Britain". Written on fragments of thin, post-card sized wooden leaf-tablets with carbon-based ink, the tablets date to the 1st and 2nd centuries AD (roughly contemporary with Hadrian's Wall). Although similar records on papyrus were known from elsewhere in the Roman Empire, wooden tablets with ink text had not been recovered until 1973, when archaeologist Robin Birley discovered these artefacts at the site of a Roman fort in Vindolanda, northern England."
Roman writing tablet from the Vindolanda Roman fort of Hadrian's Wall, in Northumberland (1st-2nd century AD). Tablet 343: Letter from Octavius to Candidus concerning supplies of wheat, hides and sinews. British Museum (London) | Author = Michel wal) | 2008. This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported, 2.5 Generic, 2.0 Generic and 1.0 Generic license.
When we look at these 2000-year old tablets, we see that not too much has changed in the shape of the "outer" rectangular design for ""thin" tablet writing that Apple has in fact copied from our forebears and to which it is wrongfully and shamefully trying to claim exclusive rights.