The bowl-shaped, six-ring species corannulene (C₂₀H₁₀) has been the subject of several unsuccessful searches toward various sources in the last two decades, with two efforts reported in 2025. First, Morán and co-workers were not able to find evidence that corannulene is present toward TMC-1 in QUIJOTE survey data collected with the IRAM 30m telescope. Most recently, Koo and co-workers did not detect the molecule toward the Red Rectangle nebula based on data collected with ALMA. In 2009, Pilleri and co-workers had sought corannulene in the same source using the IRAM 30m telescope without success. Finally, Thaddeus and Klemperer also searched for corannulene toward TMC-1 and determined it must constitute less than one part in 100,000 of the carbon in the source.

Corannulene has several unusual traits as a polycyclic aromatic hydrocarbon containing only carbon and hydrogen: it is aromatic in spite of being non-planar, it has 5-fold symmetry and falls in the C_5v symmetry group, and it has a substantial dipole moment that exceeds 2 D and is thus comparable to water. It is the last trait that makes corannulene a favorable subject for detection via its rotational spectrum. Corannulene was first synthesized by Barth & Lawton in 1966; thay also coined the name corannulene, which is much preferable to IUPAC name, dibenzo[ghi,mno]fluoranthene.