now i'm pretty sure this is a RB story, i read it when i was in school and now can't find it anywhere and am going mad.

It's about a man who's dropped off on another planet to find some kind of mineral and the ship will return in a few days, on this planet he eventually comes across this ball that is like a liquid, it chases him and has a collection of different species of things, the ball eventually catches the man but due to it's programming lets him go because whilst he was running he lost so much weight he didn't meet the weight requirements of the balls programming.

Anyone know this one? I'm pretty sure it was in the same book as 'The sound of thunder' cos i finished the first story before everyone else so my teacher gave me the sound of thunder to read whilst everyone else caught up!

Cheers

My guess, NOT a Bradbury.

Somebody here will likely soon either correct me or come up with the actual story title...

Don't know the title but I'm also going with not Bradbury. Anyone up for checking school textbook appearances of "A Sound of Thunder" to see which book may have contained such a story?