I think it was the very first prototype that a guy named Steven S., a young director, made in his garage with his own hands back in 1974, while he was in the first days of pre-production of a horror feature. He damped it in the ocean after his sister in law told him it looked like an Ed Wood creature, that this... this ... thing could not even scare a four year old girl.
In the night, at that time, young Steven regularly had scary nightmares in which he was the reincarnation of Ed Wood. Those dreams would wake him up breathless, with a cold sweat lurking all over his body.
After the secret prototype was lost in the ocean, Steven S. made a huge squale in a somewhat larger garage and became rich in no time.