Original: In their first appearance in The Tomb of the Cybermen, they resembled oversized metallic silverfish and had segmented bodies with hair-like tactile sensor probes along the base of their heads, which were topped with crystalline eyes.
Simplified: In their first appearance in The Tomb of the Cybermen, they resembled big metal fish and had segmented bodies with hair sensor probes along the base of their heads, which were topped with eyes.