The iconoclastic grosz, as it was colloquially called in the SpodStempla blog article, is a very rare, first type of Tykocin grosz. Characterized by the presence of the Jastrzębiec (Stanislaw Myszkowski) coat of arms on the reverse.
Being a heraldically controversial coin, since Myszkowski's coat of arms not only replaced the Pillars of Gediminas (the historical emblem of Lithuania), but was also placed by the engraver on a par with the royal monogram, under the prince's mitre! This may have been the main reason why the earlier iconography was quickly reverted to.
The type is noticeably rarer than the other type of grosz from this vintage (with the Pillars instead of the Jastrzębiec), which Tyszkiewicz emphasized by pricing it 20x more expensive (12.00 mk compared to 0.60 mk).