"Slan: by AE van Voight?
"Published in 1940, this is one of the first
popular novels to feature a group of people who have mutated into
super-intelligent beings — sort of X-men style — and become outcasts.
Called Slan after their creator Samuel Lann, the mutants have psychic
abilities, super-healing and enhanced agility. But some of them also
have tentacles that make them easy to spot. As humans try to hunt down
and kill these visible Slan, others go underground and try to stop the