When you read the following sentences, you will notice that a noun in the possessive case frequently functions as an adjective modifying another noun:

The miner's face was covered in coal dust.

Here the possessive noun "miner's" is used to modify the noun "face" and together with the article "the," they make up the noun phrase that is the sentence's subject.

The concert was interrupted by the dogs' barking, the ducks' quacking, and the babies' squalling.

In this sentence, each possessive noun modifies a gerund. The possessive noun "dogs"' modifies "barking," "ducks"' modifies "quacking," and "babies"' modifies "squalling."

The film crew accidentally crushed the platypus's eggs.

In this example the possessive noun "platypus's" modifies the noun "eggs" and the noun phrase "the platypus's eggs" is the direct object of the verb "crushed."

My uncle spent many hours trying to locate the squirrels' nest.

In this sentence the possessive noun "squirrels"' is used to modify the noun "nest" and the noun phrase "the squirrels' nest" is the object of the infinitive phrase "to locate."