A holding plate includes a flat base member with a surface that is formed with a plurality of stations (wells or depressions) for holding specimens. A panel extends downwardly from the edge of the surface to create a concavity for receiving a lid member therein. The panel also has a flange extending outwardly from the concavity. The flat lid member has a skirt with a rim that extends from the edge of the lid member to create a hollow for receiving a base member therein. In operation, a robot or mechanical device selectively engages the flange of the base member and the rim of the lid member to engage or disengage the base and lid members. This allows for individual movement of either the base member or the lid member. This also allows for collective movement of the engaged base and lid members for stacking and storage.