“What Pet Should I Get?” That question was posed by one of Dr. Seuss’s posthumously published titles. Not his best work, but as usual he was onto something. For kids, the choice of pets can provoke a near-existential quandary, one that can reverberate through life. Will you be a dog person or a cat person? A hamster, gerbil, guinea pig or rabbit person? Turtles, fish or succulents? Where will your love go?

You may even turn out to be a tardigrade person, at least if you read Jessie Hartland’s MY TINY PET (Nancy Paulsen Books, 32 pp., $17.99; ages 4 to 8). Tardigrades, as you know, are microscopic animals sometimes referred to as water bears, which can survive in harsh conditions. This spring they made news as payload on a private Israeli space mission that crashed into the moon; they were meant to be part of a “lunar library,” along with human DNA and most of Wikipedia in English.

Anyway, in Hartland’s whimsical yet informative book — informative, if you care to learn about tardigrades — they are the perfect pet solution for the young narrator, whose family keeps downsizing and who has already given up all manner of feline, canine, avian and piscine companions.