I couldn't find anyone pointing this out. The opening shot in "Sprivy" has the Core Drill from Tengen Toppa Gurren Lagann buried above the tunnels : r/amphibia
1082x1922px | free download | HD wallpaper: drill text, Anime, Tengen Toppa Gurren Lagann, communication | Wallpaper Flare
TENGEN TOPPA GURREN LAGANN: GIGA DRILL BREAKER!!! by recessartjunk on DeviantArt