[4] They were probably sessile and fed by filtration, although it is possible that the part attached to the substrate produced a slow displacement, at least for Vetulocystis and Dianchicystis.

[5] The affinities of vetulocystida remain unclear,[4] and the only cladistic analysis of the taxon was done as an extension of work focused on stem-chordates.

Despite noting certain shared surface characteristics with other taxa (such as Tunicata), the discovers of the first vetulocytids believed them to belong to the Echinodermata stem group, and also to be related to the taxon Vetulicolia.

[4] Another challenge to the above cladogram is the more recent majority view that vetulicolians are stem chordates, rather than being placed as basal deuterostomes.

[2] While a stem-echinoderm affinity for Yanjiahella is a matter of some debate, the proposed alternatives are also within stem- or crown-group Ambulacraria.