Specimen plate lid and method of using

The field of the present invention is the manufacture and use of lids for containers. More particularly, the present invention relates to lids for use on specimen plates, such as microplates. The specimen plate lid is generally a block, with a cover portion and a side portion. An alignment protrusion extends from the side portion and cooperates with an alignment member of the specimen plate to assist in manually or roboticly guiding the lid onto the specimen plate. An underside surface of the cover has a sealing perimeter for receiving a seal constructed from a compliant material, and shaped to cooperate with a complimentary sealing surface on the specimen plate. The lid is weighted so that when the lid is aligned and positioned on the specimen plate, the weight of the lid provides a gravitational force to sufficiently compress the seal against the sealing surface on the specimen plate. Accordingly, the lid is sufficiently sealed to the specimen plate to avoid contamination and impermissible drying.