Why Is the Duck Green?

The sky is overcast and the clouds are red. Su Huai led the team walking on the cliffside path beside the Grand Canyon. His eyes passed through the telescope and fell on the mutated giant in the shallow water below. The black octopus has as many as twenty waving tentacles, and the manta ray has its belly turned over, its expression half-smiling but not smiling. It has lost its usual cuteness and simplicity, and has become a bit more unpredictable and weird. The black seawater is as viscous as petroleum, and the gelatinous objects hit the shore with the waves, and the sand is corroded into black. Concept: Why are ducks green?