I was just looking up the verb meaning to hatch and found that apparently it's the highly defective éclore. I'm not surprised it's defective since clore is as well, but I am unsure what to use instead. There are other more common words in modern usage that have replaced clore, like fermer, but what do you use instead of éclore? Or is it still used much?
Upon further consideration though, I suppose as human beings we only ever really say "it is hatching" or "they are hatching" - the two forms that survive for the verb in the present tense. And in a children's story with a duck for a narrator they might say "I hatched" but then the passé composé tense is perfectly non-defective for éclore so that's no problem either.
I suppose the problem only arises if, let's say in a science fiction novel, an alien species were explaining to humans their biological process and were to say "We hatch after 27 days." How would that be said?