Triton says it is vanadium (V). That is vanadium in the +5 oxidation state, like VO2+. It should be yellowish, unless there is more to it that they are not indicating, such as an organic chelator.
Wikipedia has a picture of the colors as vanadium (V) is reduced to other oxidation states:
https://en.wikipedia.org/wiki/Vanadium(V)_oxide
As to the form in seawater:
"In seawater, vanadium ions are in the +5 (V V ) oxidation state as HVO 4 2-or as H 2 VO 4-ions, at very low (35nM) concentrations."
from:
https://www.researchgate.net/public...f_many_different_stories_with_a_dicey_outcomeI’m looking to do the same thing that triton uses