Peterchy[1] is an enemy first appearing in Mega Man 3. It is a reconnaissance robot consisting of a central eyeball and two plunger legs, which spins its legs around its body to walk.
In Mega Man 3, Peterchys are somewhat common, appearing in Magnet Man Stage, Spark Man Stage and Shadow Man Stage, as well as the Doc Robot versions of the latter two. They are extremely basic enemies, doing nothing but walk forward, fall off platforms and turn around when they touch a wall.
They usually appear in groups and are placed in somewhat tight spots or at the top of stairs, encouraging Mega Man to take them out with rapid fire before they can reach him.
Mega Man II
Sprite from Mega Man II.
Peterchys return in Mega Man II, where they appear in that game's version of Magnet Man Stage and Wily Stage 2. They act the same as they previously did, but are among the enemies that had their size reduced to fit the smaller Game Boy screen, making them appear diminutive in comparison.
A reconnaissance robot. Honestly, it's a small fry.
HP 03
AT 04
Related Enemies
Petaforth (Mega Man 7) - A much larger Peterchy that reaches further with its legs, but stays on platforms.
It is also possible that the Peterchy is related to the Adhering Suzy and its variations, due to both having a central eyeball and red, suction cup-looking appendices.
References
↑Mega Man: Official Complete Works art book, 2009.