Krang's extensive backstory in the original series is explained through episodes

[Jephael]

Originally Posted by CyberCubed

8 ) In, "The Four Musketurtles" we see a flashback of Krang's race and they're all brains in bubble walkers, contradicting their full body growth from Season 7. This is either a continuity glitch or before Krang managed to grow himself a body. This also proves that Krang is actually from a race in the series, whether or not they were Utroms was never explained.

How do we know they aren't different races of Dimension X creatures who had their bodies removed for some odd reason?