What exactly dark matter is remains unknown: the big bet is that it is some as-yet undiscovered elementary particle, some relic of the "big Bang" that created the Universe around 13 billion years ago.

暗物质究竟是什么目前还是一个谜。一种猜测是它是一些尚未被发现的基本粒子，约13亿年前宇宙大爆炸时产生的一些遗留物。

youdao

The poem is (brace yourself) a relic of the Dark Ages--as in chain mail, not e-mail.

FORBES: Leadership lessons from Beowulf