Samekh is written as a fully closed circle, one of only a small number of Hebrew letters, alongside final Mem, discussed elsewhere in this atlas, with no break anywhere in its outline. That closed shape sits behind one of the more striking miracle traditions attached to any Hebrew letter: the Talmud, at both Shabbat 104a and Megillah 2b to 3a, records that the two tablets of the Ten Commandments were engraved all the way through the stone, so that every closed letter, samekh and final mem included, should logically have left its enclosed centre as a loose, unsupported plug of stone; tradition holds that these letters nonetheless stood miraculously in place rather than falling out, a wonder some sources count among the ten things created at twilight on the sixth day of creation, just before the first Sabbath.
Because Samekh's closed form cannot be produced by a single continuous stroke without lifting the pen, a sofer writing it must join the curve carefully at one point so that the seam is invisible, a technical demand distinct from, but often mentioned alongside, the tablets tradition in discussions of the letter's scribal difficulty. Samekh is one of the Sefer Yetzirah's twelve simple letters, discussed elsewhere in this atlas, and its name, meaning a prop or support, sits oddly beside the tablets story, in which the letter is remembered specifically for needing no support at all.