Huxley was on the trail of a heart-shaped mystery: Around Fairmount, in south Noe Valley and Glen Park, are a number of sewer vent covers painted with a heart and a superimposed question mark and exclamation point (an interrobang). He found 26 of them from 2006 to 2008. In 2015 a new one appeared in the Mission District on Valencia at 23rd.

If you know of more, or know why they're there, wallace at eagerbeagle dot com would like to hear it.