What does the snail in Virginia Woolf's "The Mark on the Wall" stand for or symbolizes?

In this short story by Woolf,a character, probably a female, is sitting in a chair by the fire and notices a spot on her wall.  She begins a stream of consciousness though pattern about how...

Virginia Woolf's "The Mark on the Wall" concludes with the identification of that mark as a snail, this after several pages of digressions--on history, reality, society, art, writing, and life itself--incited by the flimsy ruse of an ontological inquiry. Readers have reacted variously to this revelation: As T. E. Apter notes, some, like A C. Bradbrook, have found it "exasperating" (54), while others have found the "cruelly disappointing" (Guiguet 217) or "trivial" (Apter 54) or "insignificant" (Gorsky 51) nature of the mark to be important to understanding that Woolf is proposing that objective reality is less important than the world of perceptions internal to each individual, a line of thought that leads ultimately to the idea that what the mark is "really doesn't matter" (Lumpkin 29), or the ironic Doppelganger to this idea, that "The writer deflates herself comically when the mark is revealed as a snail . . . (Gordon 167).