There they are, at the bottom of a spiral staircase: three dung beetles.
They are large and dark and arranged in a triangular pattern. They have antennae and six spindly, spiny legs. Their folded wings are a striped carapace. The rest of their armour is pebbled with a seed-grain texture that contrasts with their smooth faces. (Can you call them faces?)
They are a group of sculptures (much like the Chapman brothers' dinosaurs at Jesus College). They are not on a plinth.
And what are they confabulating about??
They seem a bit menacing, half abstract design, half sinister creepy-crawly. They are much larger than any beetle has the right to be.
But they are also fun, lurking in the basement, and not everybody finds them creepy. Ruth Allwood is the catering manager at Murray Edwards College where the beetles live, and she says:
"My favourite pieces of artwork are the bronze beetles at the bottom of the Dome staircase. [...] I always pat one of them as I go past." (Read the rest of the interview here: via the Wayback Machine).
Wendy Taylor made the bronze beetles in 2000 and donated them to the New Hall Art Collection. This was not the first time Taylor sculpted dung beetles. Here are some she did for London Zoo:

Another of her beetles was stolen in 2005/06 along with 20 other bronzes around London. Source: Guardian.
Cambridge has one other sculpture by Taylor; this one doesn't look like a beetle at all:

Title: Three Dung Beetles
Artist: Wendy Taylor
Date: 2000
What: Bronze sculpture
Where: The Women’s Art Collection, Murray Edwards College, Cambridge (free for the public to visit; every day 10-18)
This post originally appeared (only slightly altered) in 2012 on my blog ‘Art in Cambridge’: http://artincambridge.blogspot.co.uk/2012/11/dung-beetles-at-new-hall.html