Moves boulders backwards and forwards (5)

I believe the answer is:

rocks

I'm a little stuck... Click here to teach me more about this clue!

'moves boulders' is the definition.
'rocks' can be an answer for 'boulders' (I've seen this before). I am unsure of the 'moves' bit.

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for rocks that I've seen before include "Excites" , "Sways; stuns" , "Shakes violently - perhaps to mod music" , "Large stones" , "Boulders" .)

I've seen this clue in The Irish News.

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