Aggregated diamond nanorods, or hyperdiamonds, if you wanna sound cool, these are the hardest, most dense, and least compressible material we know of.

聚合金刚石纳米棒，或超级金刚石，更酷的是，这些是我们所知的最坚硬、密度最高，几乎无法压缩的材料。