Leeches and earthworms secrete cocoons of mucus and lay their eggs inside. After a few days, the mucus hardens into a hard protective capsule that’s remarkably resistant to changes in temperature and chemical attacks.
It’s cocoon’s resident is a ciliate, one of a group of microscopic single-celled creatures found in water all over the world. The ciliates have a proud scientific heritage. The first one was seen in 1674 by Anthony van Leeuwenhoek, the father of microbiology, who peered at it with his hand-made microscopes. It was then named in 1767 by Carl Linnaeus, the father of taxonomy, who called it Vorticella.
And within the inner wall, Bomfleur found a microbe that “agrees in every observable detail with the living [ciliate] Vorticella.”
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