How exactly does this Apollo astronaut's tool work? What was it called?

Question

The BBC News article Apollo in 50 numbers: Weights and Measures shows the following photo with the caption:

The astronauts brought back more than 360kg (790lb) of Moon rocks for study on Earth (Credit: Nasa)

I'm guessing that this is some kind of reach-extender to allow the astronaut to pick up rocks without needing to bend over and use their hands.

Question: How exactly does this Apollo astronaut's tool work? What was it called? The angle of the graspers looks like they would not extend around the rock to be picked up, unlike the rigid fingers shown in the second image of a modern "reach extender". How do these grasp rocks effectively? Was there a maximum size or mass they could be used on?

Cropped NASA photo:

Reach extender (rotated, flipped, from here):

Answer 1

Those are tongs.

The tongs consisted of a set of opposing spring-loaded fingers attached to a handle and were used for picking up samples. Postflight evaluation of Apollo missions 11, 12, and 14 indicated a need for increased length, larger jaws, and additional closing force. These changes were incorporated for Apollo missions 15 through 17. Also, to conserve traverse time and to afford maximum flexibility in obtaining samples, two sets of tongs were carried on the Apollo 16 and 17 missions.

Apollo Program Summary Report, section 3.2.7.1e