The item that does not belong in the group is "Owl," as it represents a creature in nature, whereas the other three items—Dagger, Blood, and Moon—are symbolic elements that relate to the themes of ambition, guilt, and the supernatural in Shakespeare's "Macbeth."
In "Macbeth," the Dagger symbolizes Macbeth's ambition and the violent means he is willing to undertake to fulfill his desires, as illustrated in his famous soliloquy when he sees the “dagger of the mind” leading him toward Duncan’s murder. Blood is a recurring motif representing guilt and the consequences of Macbeth's actions, as demonstrated when Lady Macbeth exclaims, “Out, damned spot!” showing her torment over the blood that cannot be washed away. The Moon, often associated with the supernatural and the unnatural events in the play, reflects the eerie atmosphere and foreshadows the chaos that follows Macbeth’s usurpation, as seen when he instructs the witches to "bewitch the air" and disrupt the natural order. Each of these items contributes to the dark and thematic landscape of the play, unlike the Owl, which simply exists in nature without the same symbolic weight.