This story had a researcher landing on an uncharted planet to see if it was any good for mining some type of mineral/metal. Whilst there he encounters this type of ball that chases him all over the planet. He ends up finding this ball’s collection of other things it has caught including animals all the way back to the dinosaurs. On the ball it has the writing '+/-7.

In the end it chases him for so long that he weighs too little for the balls 'collection'.

Any ideas greatly appreciated.

  • Thanks for posting this Jen. I've never heard of it before but it sounds like an interesting read!
    – SaturnsEye
    Commented Apr 9, 2014 at 9:13

1 Answer 1


There's a short story titled The Ruum (Arthur Porges 1953) that has the main elements you describe. The 'Ruum' is the 'ball' but is described as 'bloblike' in the Wiki synopsis. Also, the story takes place on Earth, not an uncharted planet.

The Ruum (shape-shifting, indestructible robot) is accidentally left on Earth by aliens during the age of dinosaurs. It's job is to collect different species of animals weighing 160 lbs (+/- 15) and preserve them in suspended animation for later retrieval.

Jim Irwin, a uranium prospector, encounters the Ruum which notes that Jim weight 149 lbs. Chase ensues. The chase causes him to lose 10 lbs so he's now outside the 'capture limits'.

Interestingly, I found another (even shorter) synopsis (actually a comparison of 'The Ruum' with 'The Zoo') and it says 'Jim who has been ordered to go back and get the H-9 Ruum they left behind on the third planet'.

Looks like the story itself is quite short and I'm still trying to find a copy of the text. Would like to verify (or refute) that tidbit I found in the Ruum vs Zoo comparison.

  • OMG I love you!!! I have been looking for this story for years! Thank you so much! xx
    – jen
    Commented Apr 5, 2013 at 20:09
  • @jen - Welcome aboard, hope we continue to see you on the site. I take it this answer rings a bell ? It would be helpful if you 'accept' it if you believe if fully answers your question.
    – Stan
    Commented Apr 5, 2013 at 20:20
  • oh right sorry, bit of a newbie!
    – jen
    Commented Apr 5, 2013 at 20:37

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