Blades are enemies in Ripple Dot Zero.
Blades are attached to a dark grey contraption at a nearly right angle. The blade itself is also grey and flashes a tint of light blue on its edges and inwards towards the knob. There are two thin bars in front of the blade that sandwich the knob.
Blades only appear in Terrarium Area 2. They can be found attached to the ceiling or on the ground. The blade constantly spins as the arm moves the blade vertically along the trajectory within the two thin bars. When the blade reaches one end of the bar's length, it will pause briefly before moving in the other direction. Only the blade itself hurts Ripple Dot Zero on contact. The rest of the parts that support the blade are harmless.
Blades can be destroyed with a single strike. This causes the blade to disappear while the rest of the contraption remains in tact.