Identify the genre of the following passage:
Suddenly, Sam looked down and noticed his skin, gradually changing to a greenish color as his legs became wobbly like jello. Was he sick? Sam tried to make his way to a chair, but felt a surge of panic as he lost control of his legs and collapsed to the floor. A tingly sensation overcame him as he could see hard, flat disks emerging from his skin. Within minutes, his scaly legs had broken through his pants and fused together. Sam was so shocked that it took him a moment to realize that he couldn't breathe.