A lid for a food storage container includes a lid body with a vacuum sense
opening and a vent opening extending through the lid body, a releasable
cover disposed over the vent opening, and a pressure-indicating
protrusion. The cover impedes air flow into the container through the
vent opening until the cover is released. The pressure-indicating
protrusion, which has a cavity in it, is in hydraulic communication with
the container through the vacuum sense opening. The pressure-indicating
protrusion contracts toward the vacuum sense opening in response to
negative container pressure.