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"All sea snakes discovered so far are venomous and produce some of the most dangerous venoms known in the animal kingdom but most species are considered to be non-aggressive."
I could have stepped on this damn thing thinking it was seaweed, and I'm sure that would have inspired some aggression that I could have found existentially distressing.
In the most Aussie scenario possible, a passerby saved the snake by taking their thongs (flip-flops) off, picking up the snake between the soles of the two thongs, and taking it to where the tide still reached. It swam off energetically.
Unrelated story: A few hundred metres up the same beach, where the sand meets rock pools under some cliffs, my (at the time ~7 year-old) son calls out "I found a squid", then 10 seconds later "it's turning blue!". His mother and I both immediately screamed DON'T TOUCH IT and started running towards him. He didn't touch it. It was a blue-ringed octopus[1]. Australian kids learn about them in primary school.