The sign for the Mayan Symbol "Baktun," used in the Long Date calendar. It equals 144,000 days.
Maudslay: PNG from Cyrus Thomas (1904) Mayan calendar Systems II
<a href="//commons.wikimedia.org/wiki/File:Baktun-Quirigua-C.png" title="File:Baktun-Quirigua-C.png">Baktun-Quirigua-C.png</a>. Traced bitmap in Inkscape.