Under white light, the squat urchin shrimp (Gnathophylloides mineri) disappears completely among the spines of its Caribbean host. Its striped body and mitten-shaped claws mimic the urchin’s surface so precisely that the parasite can graze unnoticed on the spine’s epithelial layer. Yet under 450 nm fluorescence, the deception dissolves—the urchin glows deep burgundy while the shrimp flares chartreuse, exposing its presence in luminous contrast. What appears as a quiet refuge by day becomes, under the right wavelength, a revelation of intimacy, dependence, and disguise.