nice to know I'm not the only one who calls it the thunder shield instead of lightning

I was working with the Fire shield and I noticed two purple pixels, one in the last sprite of the Fireball Spin Dash, and one in the 3rd front layer sprite (Fire Shield > row 2 > column 6). A quick check at some YouTube video shows that those pixels are supposed to be empty, so I suspect it to be some leftover from some background magenta not replaced with transparent color then new dark green background when moving to this sheet. The video resolution was not great, this should probably be confirmed with some proper 1:1 emulator check. Anyway I'll remove the pixels manually for now.

Thanks to Aseprite > New Palette from Sprite feature to make it easier to spot pixels out of color palette!

I was today years old when it occurred to me that there is no generic shield in Sonic 3.

FIGHT! FIGHT! FIGHT!

we don't need your ocd here

The center point on the Insta-Shield's fourth frame should be 7 pixels left and 10 pixels down, and the center point on the fifth frame should be 7 pixels left