“No antivenom” is the sentence that gets repeated until it sounds like the shore should be closed. It should not. There is no antivenom because the sensible and effective response to this animal is distance, and because the medicine that saves people is ventilation, which hospitals already know how to do. The missing vial is not a mystery curse. It is a reflection of a bite that almost only happens when a person has picked up, stepped on, or cornered a very small octopus.
The beach remains usable because the animal’s behavior cooperates. It hides. It flees. It signals. It bites when those have failed and it is being touched. A swimmer who is not turning over rubble with bare hands, not putting shells and bottles into a bucket for later inspection, and not showing a child “a little octopus,” is a swimmer who has already done the prevention that an antivenom would be trying to repair.
Public aquariums, local signs, and the occasional news story are doing the same job as the rings. They are asking for the signal to be believed in advance. Once a bite has happened, belief is no longer the point. Breathing is the point, and then a ventilator, and then time. Communities that actually live with these animals do not treat every pool as a hazard zone. They treat handling as the hazard.
If you want a rule that fits on a sign, use this one. Nothing in a tropical or southern Australian pool needs to be picked up to be admired. The animals that are safe to touch are not your sorting problem. The animals that are not safe are small enough to look harmless. Leave the sorting to the rings.