The SI prefixes above are not the only extreme ones. Others such as xenno (x) (10-27) and xenna (X) (1027), or vendeko (v) (10-33) and vendeka (V) (1033) exist, and can help simplify the expression of extreme numbers.
'Now we're talking xennobiology!' [...] a complex organism based on similar processes to the primitive ones they'd seen probably would be about a xennometre in size.