The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk.
In gastropods, the body whorl, or last whorl, is the most recently formed and largest whorl (or revolution) of a spiral or helical shell, terminating in the aperture. It is called the "body whorl" because most of the body of the soft parts of the animal fits into this whorl.
The proportional size of the body whorl in gastropod shells differs greatly according to the actual shell morphology. For shells in which the rate of whorl expansion of each revolution around the axis is very high, the aperture and the body whorl are large, and the shell tends to be low spired. The shell of the abalone is a good example of this kind of shell.
The opposite tendency can sometimes create a high spire with very little whorl increase per revolution. In these instances, e.g. in the shell of Turritella species, both the body whorl and the aperture are relatively small.
One night as I lay dreaming of pleasant days gone by
My mind was bent on rambling to Ireland I did fly
I stepped on a vision and I followed with the wind,
When at last I came to anchor at the cross of Spancill Hill.
Then on the 23rd of June the day before the fair,
When Ireland's sons and daughters and friends assembled there.
The young, the old, the brave and the bold came their duty to fulfill
At the Parish Church in Clooney a mile from Spancill Hill.
I went to see my neighbours, to hear what they might say,
The old ones were all dead and gone, and the young ones turning grey
I met the tailor Quigley, he's as bold as ever still,
Sure he used to make my britches when I lived in Spancil Hill.
I paid a flying visit to my first and only love,
She's as fair as any lily and gentle as a dove
She threw her arms around me, saying "Johnny, I love you still"
Ah she's Ned, the farmer's daughter, the pride of Spancil Hill
I dreamt I held and kissed her as in the days of yore
"Oh Johnny you're only joking, as many's the time before"
The cock he crew in the morning, he crew both loud and shrill,