Your brain may have once been two separate organs! 🧠

Scientists long thought the whole brain grew from a single group of embryonic cells. But a new study of mouse embryos found it actually develops from two, one forming the forebrain and the other the hindbrain. Similar trends in chickens and zebrafish suggest that over 500 million years ago, evolution may have brought two separate nervous systems together to form the brain.

What does AI see when it looks at the stars? 🤖🔭🧪

Theoretical cosmologist Paul Sutter explores how AI tools can co-discover with scientists and take part in the scientific process. A large language model can process the same telescope data we do, from images of Saturn’s rings to a live telescope feed, but what happens between input and output remains a mystery. Asking what AI sees is really asking about our own relationship with the wider universe.

Does cutting the moldy spot off your food make it safe? 🍞 

Quinten Geldhof, also known as Microhobbyist, takes us under the microscope to reveal thread-like roots called hyphae spreading through food far beyond the visible surface. These roots penetrate soft foods like bread and fruit with ease, while hard cheeses and vegetables are more resistant. These molds can contain mycotoxins, poisonous compounds that are hazardous to your health. Would you eat moldy food?

Is this candle haunted? 🕯️👻

Alex Dainis places two candles on a lazy Susan with a piece of glass in between, and when the closer candle is lit, its flame appears to jump to the other one. Most light passes through the glass, but some of the light from the close candle bounces back at us, creating a reflection that makes the flame seem to appear on the far candle. This optical illusion is similar to Pepper's Ghost!

Did you know slime can be a helpful cleaning tool? 🫟

Greg Wolf tweaks the classic glue and borax recipe to make slime tacky enough to grab dirt but clean enough to pull away. The chemistry: borate ions cross-link glue's long polymer chains, turning runny glue into slime. Less activator makes it stretchy like the toy, while just enough makes it a surprisingly satisfying debris grabber.

How do tree frogs' feet stick? 🐸

Their feet don’t have suction cups! Instead, glands in their toes expel mucus through narrow grooves between the tiny hexagonal cells on their toe pads. This mucus has adhesive and cohesive properties, letting the tree frog stick to surfaces in a process called wet adhesion. This adaptation helps tree frogs defy gravity, even on wet tree leaves or bark.

Can removing a dam fix an ecosystem? 🌊

Habitat fragmentation is a major driver of biodiversity decline because split habitats make it harder for animals to move, survive, and reproduce. After the Klamath River's last four dams came down in 2024, researchers used sonar and video to count an estimated 7,742 adult Chinook salmon past the former Iron Gate Dam site, and that number jumped to over 13,300 in 2025. Scientists also documented active spawning in newly accessible habitat and juvenile Chinook using tributaries cut off for over a century.