In the halo essential visual guide it confrims that a early precursor not exactly" the timeless one" from halo cryptum turned into the gravemind on page 81 middle right connor in “origin of a gravemind” it states " a gravemind begins with a coalescence of raw, organic material ( predominantly that of a sentient creature) and the fusion of the fcs, resulting in what to be known as a proto-gravemind, an early precursor to the gravemind itself". fo in halo crytum sequal coming in 2012 we might see the timeless one turn into a gravemind and have a long 43 year talk with medicant bias.
You can’t be serious
Although I do think there is a connection between the Gravemind and the Timeless One, the description in that book isn’t even close to being proof.
Precursor - Noun
A person or thing that precedes, as in a job, a method, etc. Predecessor.
The Proto-Gravemind is the predecessor of the Gravemind.