About "-us" and "-um" as far as plurals are concerned

     I have stumbled upon a post by lexico saying that "cacti" is wrong, and so is "viri".  They are wrong.  Their logic is that since these words aren't latin in origin, we can't pluralise them with -i.  Pay no attention to these ignorami.  It is only correct to pluralise multisylabic words ending in "-us" and not in "-ous" with "-i" or "-odes".  ie. "cactodes" and "cacti" are correct, but "cactuses" isn't, despite what Lexico would have you believe.  An exception to this rule is "nucleus" when used in the context of a cell.  Also, Lexico says "algæ", of all things, is correct, and the plural of "alga" as opposed to "algie", "alge", "algea" being the correct way to refer to it.  Algea is the correct term which is an uncountable noun, and the word "alga" which Lexico made up should only be used if you are writing for those people at Lexico.  Also, as per usual, any backformed singular is perfectly fine, even if the back formation is done from the "-odes" plural as in using "cactode" to refer to more than one cactus.

CHANGE MY MIND!!!

//this blog has been really fun to write, just coming up with nonsense grammar to prescribe as "correct" on this style guide has been very enjoyable.