On 22 July 1958 a South Pacific teenage squid known only as Janice was swimming off the coast of the Bikini Atoll when she saw a blinding flash of light in the sky, it was a nuclear explosion! As she swam through the warm waters, radioactive carbon fallout fell like snow on the sea and within minutes, Janice's body was infused with radioactive molecules and she was transformed into Diamond Squid.
Filled with rage at the destruction of her South Sea habitat, she wove herself a cape of radioactive seaweed and swore to use her new superhard body, miraculous powers of flight and the ability to transmit laser beams to fight the evil empire of the United States and bring their nuclear testing programme to an end.
Thanks @opheliafu for the inspiration :)