In subtle and not-so-subtle ways, seniority means something in religious life. From deference at table to who gets his choice of rooms, one's 'age in religion' comes into play.
In past generations, one's biological age and religious age were often more or less the same. Most candidates came to the community at the same or very similar ages, and so seniority tended to match up with age.
Of course this is no longer the case. Candidates come to religious life at quite a range of ages. Some are right out of high school while others have already had whole careers in the world. Most communities have an age limit for entrance, but these tend to be generous and even with them exceptions seem to be common.
I've just been thinking about this little topic as I try to reflect and pray about this friary in which I've been asked to be the guardian or 'local superior.' By age in this world, I am the third youngest of eight friars. But by age in religion, I am the second most senior. It's a curious thing.