91É«ÇéƬ

What are these soft, white balls, about 5 centimetres long, found under a drain cover (pictured)?

Roger Hooper,

Llechryd, Ceredigion, UK

Ìý

Why are many people squeamish about the sight of blood when, for much of history, we had to butcher animals?

Derek Johnson,

Moreton-in-Marsh, Gloucestershire, UK

To answer this question – or ask a new one – email lastword@newscientist.com.

Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address.

91É«ÇéƬ retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format.

Terms and conditions apply.