Scientists have reconstructed what a Jurassic forest might have sounded like 165 million years ago, and the one-minute audio is a really cool soundscape to imaginatively step into. They created it by analyzing and modeling the sound-producing structures preserved in 20 fossil insect wings from nine species that lived together in what is now Inner Mongolia. It’s a diverse chorus of low trills and high-pitched chirps, and I wish I could loop it all day as background noise. — CD

Inexpensive exercise headphones

If I'm doing vigorous exercise, my earbuds fall out. I didn't want to spend a lot of money on a second pair, so I bought these inexpensive Joywise Bluetooth headphones. They are wireless, have loops that fit around the ear, and are connected to each other with a wire. Unlike most small earbuds, they charge via USB-C directly rather than in a case. The sound quality is great for the sub-$20 price, and the batteries last up to 16 hours before needing a recharge. — MF

Analog math

For mathematical nerds, Henry Segerman is your channel. Segerman 3D-prints weird mathematical shapes, invents curious mathematical toys, constructs intricate mathematical models, and turns math into analog things you can 3D-print yourself. His YouTube channel demos all this with expert explanations of the math behind it. — KK

Free online utilities

Normal Tools is a free collection of 193 single-purpose tools for all kinds of random small tasks, including calculators, color pickers, image resizing, and file conversion. It has more tools than I will ever need, but useful to bookmark. Most tools are private by default and process everything locally in your browser, with no account or download required. — CD

China Travel

I am traveling in China again and I am reminded that the best way for foreigners to book hotels, trains, and flights anywhere within China is to use Trip.com. It is easy to use, comprehensive, accurate, and reliable. — KK

The White Rose

Besides Recomendo, Cool Tools publishes a newsletter about books called Book Freak. I've been doing it for quite a few years, and I recently started finding old out-of-print books, scanning them, and turning them into ebooks with a new foreword and cover. This is a benefit for paid subscribers, and so far the library includes four books, with a new one coming every month. The latest is The White Rose by B. Traven, who also wrote The Treasure of the Sierra Madre. It was translated into English in 1979 but is out of print, so I used AI to translate the German version. It's very readable and a fantastic book. You can read about it here. —MF

This Issue’s Sponsor

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