furcula

A forked process or structure, generally two-pronged.

The forked bone formed by the fusion of the clavicles in birds, the wishbone or merrythought.

The (two-pronged) forked, somewhat tail-like organ held bent forward and secured by a catch beneath most species of Collembola (springtails), with which they jump by releasing the catch abruptly when alarmed.

In essence, a furcula is a long, rigid stick, held underneath the body at high tension. When the springtail releases that pressure, the stick pushes down into the ground, or even the water's surface, like an upside-down medieval catapult, firing the springtail into the air in a semi-controlled manner.