Strange plural pairs [closed]

I don't speak German but was fascinated to learn that in (Swiss or I believe Bavarian) German Rahm means cream, but Rahmen means frame - despite adding "-en" being the normal way to make a singular word plural. Rahm apparently has no plural (and/or is the same in the plural, like the English "sheep") and Rahmen is the same (i.e. the words for frame and frames are the same).

So I set out to find similar examples in English, i.e. where:

1. Word 2 looks like the plural of Word 1, but is not

2. Word 1 either is its own plural or has no separate plural

3. Word 2 either is its own plural or has no separate plural

The closest I can find are:

• physic (medicinal drugs - apparently it's own plural - or the study of medicine), and physics (the branch of science concerned with the nature and properties of matter and energy, having no plural).

• corp (corporation) and corps (body of people). Doesn't quite work as if "corp" is a word, I think it has "corps" as a plural which would break rule 2.

Can you do better?

Solution 1:

How about (the) new (new things; a noun that has no plural) and news (information or reports about recent events; another noun that has no plural)?

Solution 2:

Specie: coins, especially those made of valuable metals.

This has no plural, because it's an uncountable noun.

Species: a set of animals or plants, members of which have similar characteristics to each other and which can breed with each other.

The plural form of species is unchanged.

Solution 3:

(The) rich (rich people considered together as a group; plural only) and riches (a large amount of money or valuable possessions; also plural only) satisfy your 1-3, as riches looks like the plural of (the already plural) rich (cf. ostrich, or if you want to avoid an argument about that, then perhaps bitch).