  Usually, a loose stellar distribution can be classified as an OB stellar
group, an association, or a young open cluster. We make use of comparisons with
the typical OB association Vul OB1. In the present paper we discuss the nature
of Bochum 1, a typical example of an object affected by the above
classification problem.The field-decontaminated CMD of Bochum 1 presents main
sequence (MS) and pre-main sequence (PMS) stars. We report two new small
angular-size, compact young clusters and one embedded cluster in the area of
Bochum 1. Vul OB1 harbours the young open cluster NGC 6823 and the very compact
embedded cluster Cr 404. The Vul OB1 association includes the H II region
Sh2-86, and its stellar content is younger ($\approx3$ Myr) than that of Bochum
1 ($\approx9$ Myr), which shows no gas emission. Bochum 1 harbours one of the
newly found compact clusters as its core. The RDP of Bochum 1 is irregular and
cannot be fitted by a King-like profile, which suggests important erosion or
dispersion of stars from a primordial cluster. Similarly to Bochum 1, the
decontaminated CMD of NGC 6823 presents conspicuous MS and PMS sequences. Taken
separately, RDPs of MS and PMS stars follow a King-like profile. The core shows
an important excess density of MS stars that mimics the profile of a post-core
collapse cluster. At such young age, it can be explained by an excess of stars
formed in the prominent core. The present study suggests that Bochum 1 is a
star cluster fossil remain that might be dynamically evolving into an OB
association. Bochum 1 can be a missing link connecting early star cluster
dissolution with the formation of low-mass OB associations.
