The sprite file at the link on the Resources page for this lesson:
is screwed up. It came up as the lesson, with a giant spikes image that is super low resolution (2500 x 2500), way down at the bottom of the page - I almost missed it.
I just grabbed the image and shrunk it in GIMP, but you might want to fix the link and file, so it matches the rest of the course in quality.
P.S. I suggest you delete message after this is fixed, as this message will irrelevant then. J.