Haeckelites are members of a proposed family of hypothetical carbon allotropes.
The carbon atoms would be arranged in a trivalently coordinated structure generated by a periodic arrangement of pentagonal, hexagonal and heptagonal carbon rings.
They have not yet been synthesised in the laboratory, but have been the subject of a considerable amount of theoretical work and numerical simulation.
They were first proposed by Humberto and Mauricio Terrones and their colleagues in 2000.
[2] They were named in honour of Ernst Haeckel, whose diagrams of Radiolaria and Phaeodarea contained similar structural features.