I’ve dived in the Mar Menor in Spain, and walked on the shores of the Baron Island. The shores on the island are literally full of oyster shells, but I’ve never seen one on the seabed. The decline of mollusks and their filtering function is one of the factors in the decline of the water quality that has reduced the biome’s diversity. Tha major factor is fertilizer runoff from intensive farming nearby.

The “Botijo” uses the same principle and has been in use for centuries in Spain to cool water.

The article mentions fragility, but I imagine that some open sided fiberglass cage or equivalent could be made. Fiberglass is fairly low tech nowadays, cheap and widely available even in the developing world.

I agree. I-m an accomplished cook, but I enjoy the almost set and forget that my Thermomix affords me. I am tempted to get an instant pot type and with my smart Microwave have a semi robotized kitchen.

Is the new one stainless steel? If so there are very few parts that may fail, valve parts and gasket essentially. Instant pots have a ton of failure points. The modern stovetops are almost buy it for life.

I have a modern stovetop stainless steel pressure cooker, very common type in Europe. It has three redundant pressure / over pressure relief safety sytems plus a very hard to circumvent locking mechanism that only unlocks at ambient pressure. Instant pot types look interesting, because they expand on the concept, but a major drawback I see is that they are often small (my pressure cooker is 6L) and, basically a dealbreaker for me, the vessel is usually plastic coated, I.e. non/stick. I think I will stick with mine, which coupled with a programmable stovetop induction single heater I own, fulfills part of the features.

Cost per liter including filters, liquids and electricity?