Note: This page is taken from n.wikia.com.
(As written in the N in-game help)
These guys are pretty fair: don't touch them, and they won't blow you up.Mines are by far the most common enemy in N. They stay innocently in one spot, until the player touches them... and then they explode, blowing the ninja into five lifeless limbs.
Most situations dealing with mines will have the player finding a way through or around them. 25-2: mine field is an example of mass mines leading to frustrating situations. N users may create "mine jumpers", maps that are based on jumping through mines galore.
Mines can also make effective barricades. A well-placed mine or group of mines will force the player to take a different route. For example, in 54-2: so far away, one will have to slalom through the tiles due to mine rows blocking the way.