Plastoid infiltration droid

An incredibly sophisticated bio-droid that was developed by Cestus Cybernetic's along with the JK Droid during the height of the Clone Wars. The Plastidroid was an infiltrator combat droid who, in their inert form, resembled amorphous bundles of technology. Inside this shell were various components from limbs to weapons that could assemble together when commanded to with no damage to the 'skin' which could conform to any shape that the droid took. This allowed to droids to move fluidly through difficult terrain without any damage to its internal components. When completely assembled, the droids were five meters tall and used a tread based form of locomotion.

A group of these droids along with JK droids infiltrated a Republic camp on Ord Cestus, nearly wiping out the resistance fighters assembled.

Source

 * Star Wars: The Cestus Deception