Photo taken in a garden in Singapore. The organism is attached to a stone, close to water. Many of these were there.
Size approx 3cm.
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They are Apple snail's eggs; check the picture:
This could very well be the eggs from an apple snail (family Ampullariidae).
According to Wikipedia
Several apple snail genera (Pomacea, Pila and Asolene/Pomella) deposit eggs above the waterline in calcareous clutches. This remarkable strategy of aquatic snails protects the eggs against predation by fish and other aquatic inhabitants.
If these are in fact the eggs from an apple snail, then the parent is likely in the genus Pila since this is the only major genus found in Asia [source].
You can see a timelapse video of a snail laying eggs here and a short gif below:
See applesnail.net for more info.