The Natural Shell is a ribald poetic form intended to express pleasure with the concept of nature, originating in The Admired Storms. The rules of the form are applied by poets to produce individual poems which can be recited. The poem is six to seven quatrains. A form of parallelism is common throughout the poem, in that certain lines use the same placement of allusions. Each line has seven syllables. Every line of the poem has an initial caesura. The fourth line of each quatrain reverses the grammatical structure of the second line.