Floating Mines are large spheres, tan in color, with several spikes jutting out. They generally bob along the surface of layer 3 water at either a faster or slower speed. They are also found falling in the depths of the Sunken Ghost Ship. Mario cannot touch them unless he is spin jumping, in which case he will bounce off of them. Floating Mines, as inanimate objects, are immune to most of Mario's attacks. Fireballs and cape swipes do nothing, nor do thrown objects, but Yoshi can eat them. Additionally, a star can defeat them.
Floating Mines are sprite A4. They use Mario's palette 8, so keep this in mind if editing their graphics. Their graphics will only show up with the rope enemy set. (SP4=05) Floating mines' speed is affected by their x position.
Related ROM Addresses
0x0B886 [AA] Floating Mine tilemap (The value is the tile used by first frame, which is then flipped horizontally and vertically. The tile to its right will automatically be chosen for the second frame)
0x0B862 [31 71 A1 F1] Floating Mine's Flip/Palette/GFX Page