The plural of octopus is octopuses; octopi is considered grammatically incorrect. "Tentacle" is used as an umbrella term for cephalopod limbs, and is reserved for grasping and feeding appendages not found on octopuses (which have arms); up to the early 20th century "tentacles" were interchangeably called "arms."
Malcom King character shares name with famous leaders for civil rights: Martin Luther King, Jr. and Malcolm X.