Board Thread:General Discussion/@comment-31283382-20140611172614/@comment-1268838-20140923234259

Yeah, unless White existed way back during TBtP, which the dialogue in EBtR heavily contradicts, the Hollow souls used on the Visored had to have been based on ordinary souls. Thinking back, having a Shinigami-based inner Hollow is exactly what makes Ichigo unique among them.

Keeping in mind of course, that the entire point of Hollowfication is to merge two souls to increase the strength of one of them.