We wrote yesterday about Cones and their new potential gelato flavor, but the place may have bigger worries than making room in its display case. In this week’s Openings Rob and Robin introduce us to Grom, the first U.S. branch of an Italian chain. The menu, served up here first, shows this may soon be one of the city’s leading gelaterias. Along with some conventional American flavors, you’ll find cassata Siciliana (stuffed pound cake) with candied lemon, orange and cider; fiordilatte (whole milk); and sorbet and granita made with Sfusato lemon from Amalfi. Grom’s major rivals, il laboratorio del gelato and Cones, are from New York and Argentina, respectively. Will they be able to compete against the motherland? Only extensive trials on repeat visits, preferably on hot days, will tell.