In English, we have a handful of pluralia tantum that are mass nouns which take the plural form (e.g. "riches" and "remains"), a whole load of pluralia tantum that refer to things that come in pairs (e.g. "trousers", "sunglasses", "knickers", or "scissors"), and at least one plurale tantum that fits into neither of the above categories ("clothes", meaning multiple items of clothing - it's clear what the hypothetical singular "clothe" would mean, yet it mysteriously isn't a word). Singularia tantum, on the other hand, seem less varied. As far as I can tell, they are all mass nouns - things like "information", "milk", and "racism".
One can imagine there being a singulare tantum that is not a mass noun. For example, we can imagine an alternate universe in which it is still correct English to talk about "a dog", but talking about "dogs" in the plural is incorrect and funny in the same way that it is incorrect and funny to talk about a "scissor". It might seem unintuitive to think that such a noun even could exist - surely, if it is not a mass noun, then people would just pluralise it with an "s" on the end like most other words? But the converse argument could just as well be made about countable pluralia tantum, and I still cannot go to a shop and buy a "clothe". Hence my question: do we have any such countable singularia tantum in the language? Have we in the past?