Sylvia Plath's poem, "Medallion" is about a snake she finds dead, and the details of its body that she notices. Written in 1959, its form was strictly "controlled." Plath uses imagery, literary devices, and sensory details, especially colors.
First, we "see" the image of a snake, bronze, lying in the sun near a gate with a "star and moon" design.
By the gate with star and moon
Worked into the peeled orange wood
The bronze snake lay in the sun
Next, Plath uses a metaphor, comparing the snake to a shoelace. The snake is dead, but the author uses personification to describe the snake's pliable jaw and "crooked grin."
Inert as a shoelace; dead
But pliable still, his jaw
Unhinged and his grin crooked,
A metaphor is used again; it describes the snake's tongue. It is a "rose-colored arrow." Fearlessly (in death, or is the speaker comfortable with snakes?), she hangs the dead creature over her hand, noticing his "vermillion" (red or reddish-orange) eye.
Tongue a rose-colored arrow.
Over my hand I hung him.
His little vermilion eye
The poet's description of the snake's eye continues into the next stanza; it is not only red, but seemingly like fire captured in glass, which she notices as she turns him in the sunlight. At the end of the stanza, she begins a thought, recalling a moment in the past when she "split a rock."
Ignited with a glassed flame
As I turned him in the light;
When I split a rock one time
The memory of that "split rock" comes back: inside the rock were garnets that burned with the same fiery red color. The poet notes that "bust" changed the color of the snake's back to ocher which is:
...[a] color...ranging from pale yellow to an orangish or reddish yellow
"Bust" here may refer to the snake's broken back, for we find later that it was obviously killed with a brick, so that death may have changed the snake's color, especially with its placement in the direct sun. However, the speaker does not praise or admire the color, but compares it to a color on a trout that has been left out in the sun—its color "ruined."
The garnet bits burned like that.
The way sun ruins a trout.
As the writer continues to examine the dead snake, she notices the the belly still has the color it had in life—the word "fire" inferring that it is still beautiful and vibrant. Reference to the snake's chain-mail would seemingly refer to its protective skin, toughened because a snake travels on its belly. "Old jewels" may refer to old colors that are still visible, smoldering—glowing like the embers of a fire...
Yet his belly kept its fire
Going under the chainmail,
The old jewels smoldering there
...in each scale of the belly. Another metaphor compares the colors to a sunset viewed through milky white glass...and then she sees the maggots, they "coil"—like a snake...
In each opaque belly-scale:
Sunset looked at through milk glass.
And I saw white maggots coil
The distasteful "worms" are described with a simile: as thin as pins. They are visible through the bruised flesh where its "innards" bulge as with a meal...
Thin as pins in the dark bruise
Where innards bulged as if
He were digesting a mouse.
Straight like a knife, in death the snake is pure. It is evident that its death came at the hands of the yardman, who threw a brick, and laughed. There is a sense of sorrow at the loss of such beauty.
Knifelike, he was chaste enough,
Pure death's-metal. The yard-man's
Flung brick perfected his laugh.