Diagnosis. Tubular structures that radiate away from fractures, vesicle walls and inwards from the margins of volcanic glass fragments. Tubes range in diameter between c. 0.4 µm and c .6 µm with an average diameter of 1.4 µm and the mineralized tubes being higher in this range (data presented by Furnes et al. 2007, fig. 6). Their lengths are highly variable, from a few microns to several hundred microns, with only limited variation in diameters along their lengths. Tubes may be straight, curved, branched or helical, and may exhibit  annulations along their walls. They occur as isolated tubes or dense clusters of subparallel tubes that may be hollow, partially or wholly infilled with mineral phase(s).

Differential diagnosis. Unbranched, unornamented tubes with a straight to curvilinear growth axis. These are the simplest morphological form of the genus Tubulohyalichnus igen. nov.