slide
A dry mount slide is a slide that has no liquid or cover slip. This type of slide is commonly used for observing solid specimens under a microscope.
A wet mount slide is made by placing the specimen in a drop of water on the slide and covering it with a glass slip. This technique is commonly used in microscopy to observe living organisms or specimens in their natural hydrated state.
so that when viewing the specimen the cover slip won't move.
Excessive use of a slip-n-slide can lead to the grass underneath becoming compacted or damaged, especially if the slide is left in one spot for an extended period. It's a good idea to periodically move the slide to allow the grass underneath to recover. Additionally, setting up the slide on a softer surface like sand or a tarp can help protect the grass from damage.
It is called a coverslip. It is used to protect the specimen on the microscope slide and to keep it in place while observing under the microscope.