In the name Achlyophage Symbiote, we find a combination of ancient greek words that when put together, don't really make an english word. Achlyos (Αχλ­­ύος) can mean 'Night', 'Dark', 'Mist' that sort of thing. And Phagos (Φάγος) meaning 'Glutton' 'Eater' or 'Consumer'. Combining the two create this personification of a creature or artifiact that "Eats darkness." The word symbiote is one of the two organisms involved an a symbiotic relationship. Which if you haven't taken biology yet, a symbiotic relationship is a relationship two organisms have together in where one or both of the organisms is benefited by said relationship. I.e. Oxpecker and the Rhino. The helmets quote says "They told me it would eat my thoughts and leave me full of light." So I imagine that the original wearer of this helmet was told that the helmet was an organism that would consume the dark thoughts inside their head and leave them full of light thoughts. But the quote is insinuating that something had gone wrong. It says "They told me-" as though they had told him falsely and he is being accusatory. So the name describes that this helmet is intended to consume darkness in whatever organism wears it. But the quote implies that it fails to do this. I'm not sure of the design and the lava like slime substance -- that appears to move -- on the helmet. I feel it resembles a side effect the helmet has when the dark thoughts are consumed