balane

barnacle, especially the acorn barnacle; glans

“De bled en herbe vous faictez belle saulce verde [...] laquelle [...] dilate les vases spermaticques, abbrevie les cremasteres, expurge la vessie, enfle les genitoires, corrige le prepuce, incruste le balane, rectifie le membre.” — Of corn in the blade you may make good green sauce … which … dilates the spermatic vessels, shortens the cremasters, purgeth the bladder, puffeth up the genitories, correcteth the prepuce, hardens the nut, and rectifies the member.

Borrowed from Latin balanus, from Ancient Greek βάλανος (bálanos, “acorn”). Cognate with Catalan bàlan, Italian balano, Portuguese bálano, Spanish bálano.