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A deep-sea snail with iron in its scales

Some scaly-foot snails near deep-sea hot vents have overlapping foot scales infused with iron sulfide. They secrete sulfur compounds into the scales; iron from vent water diffuses in and reacts, forming tiny mineral crystals. The result differs by location: black snails from one vent field have iron-infused scales, while white ones from another lack this mineralisation. They are the same species, with different mineral finishes.

Iron-infused black scaly-foot snail on the left; pale non-mineralised snail on the right — JAMSTEC / University of Tokyo (2019), Figure 1. Kairei iron-infused snail on left; Solitaire non-mineralised snail on right. Original comparison; scale bars retained.

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Pandi2d

A jug that makes you solve a puzzle to drink

How do you drink from a jug with holes around its neck? Puzzle jugs were made for tavern drinking games: tip one like an ordinary jug and the drink spills out. The solution is hidden inside. In this design, a passage through the handle connects the drink to the rim. Cover the right openings, then suck through a spout instead of tipping. The pottery turns a wrong move into a practical joke.

An 18th-century puzzle jug with pierced neck and multiple rim spouts — Victoria and Albert Museum, London. Bristol puzzle jug, about 1770–75, museum no. 275-1896. Original photograph.

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Humans to Mars: Fifty Years of Mission Planning, 1950-2000by Pandi2d

Why did von Braun plan a polar landing?

In von Braun’s historical expedition concept, the first crew would land a glider on a Martian polar ice cap because he believed the caps were the only places where a smooth landing site could be counted on^[1]. The equatorial base site, by contrast, would be chosen later through telescope observations from Mars orbit^[2].

That separation made the first landing only the start of the surface journey: the crew would abandon its glider, travel roughly 4,000 miles overland to the selected site, and build a landing strip there for two wheeled gliders carrying the rest of the surface party^[3]. It was a proposed architecture, not a flown mission or a present-day landing recommendation^[4].

Would you also like to know how von Braun’s later, smaller Mars proposal differed from the polar-landing concept?Answer complete. One follow-up option available.

Walking To Olympus An EVA Chronologyby Pandi2d

Apollo 14’s Lunar Rickshaw: Useful, Until the Boulders

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Pandi2d

The planet with a comet-like tail

That fuzzy streak is not a comet: it is Mercury. Its tail appears in specially filtered, long-exposure photographs, making the smallest planet look as though it trails a comet. Sodium atoms escaping Mercury glow in sunlight, and sunlight pushes them away from the Sun into a tail. The same element gives some streetlights their yellow glow. As Mercury travels around the Sun, spacecraft measurements show changes in the tail’s brightness and extent.

A real filtered long-exposure photograph of Mercury and its sodium tail — Andrea Alessandrini / NASA APOD (2020). Filtered long-exposure photograph of Mercury’s sodium tail; original credit retained.

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Pandi2d

Letters folded into their own security locks

Before envelopes, people could turn a letter into its own lock. Folds, slits and paper strips secured the message and could show if it had been opened. Some designs threaded a strip cut from the letter through the folded packet. Researchers read a sealed letter from 1697 without opening it: X-ray scans captured its folds, and software unfolded the sheet virtually. The message survived, along with the original paper lock.

The unopened 1697 letter from the Brienne Collection — Courtesy of MIT Libraries / Unlocking History research team. Original photograph of the unopened 1697 letter.

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Pandi2d

A lizard with its own breathing bubble

Water anoles can dive in tropical streams and hide from predators while breathing through a bubble on the nose. Their water-repellent skin holds air: they exhale into the bubble, then breathe that air back in, repeating the cycle underwater. Researchers tested whether the bubble helps. Anoles able to rebreathe normally stayed submerged an average of 32% longer than lizards whose bubble formation was impaired, giving them more time underwater to hide.

A water anole with a breathing bubble above its nostrils — Lindsey Swierk / Binghamton University. Original photograph of a water anole with its breathing bubble.

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Pandi2d

The mushroom that hunts microscopic worms

Oyster mushrooms are carnivores: the fungus behind this familiar food can paralyse microscopic worms called nematodes, then digest them for nutrients. The hunt takes place along fine fungal threads. Tiny lollipop-shaped structures contain a toxin; when a nematode touches one, it can be paralysed within seconds. The fungus grows into the immobilised worm and feeds on it, gaining nitrogen. Beneath a fallen log, those mushrooms may conceal a miniature hunting ground.

Cultivated oyster mushrooms growing from a bucket — University of Wisconsin–Madison Extension, Bill Klase. Cultivated oyster mushrooms; original photograph.

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The World Of Wondersby Pandi2d

The Towering Termite Nests of Senegal

ten or twelve feet above the level of the groundThe World of Wonders^[1]

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Pandi2d

A mirror with a secret in its reflection

An old bronze mirror holds an image of Buddha that appears on a wall when light shines on its polished face. The picture is concealed within the mirror, not visible as an ordinary design. Tiny distortions in the reflective surface, created during polishing above the hidden design, redirect the light to form the image. A CT scan revealed the concealed metalwork in detail; the picture was built into the object all along.

The bronze mirror projecting its concealed Buddha image onto a wall — Rob Deslongchamps / Cincinnati Art Museum. Buddhist bronze mirror x1961.2, original photograph.

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