Sayana says urvArukam = karkaTiphalam = kakaDi in Hindi.
There are varieties of Indian traditional kakadi (before english cucumber came to market)
Below are some pics that I can recognise from my grandparent's farm I would visit in summer vacations.
These karkaTi, when on the vine, and not yet ripe, are very difficult to pull off the vine. You can pull and pull as much as you want, and it won't come off. You need a knife.
But when it is ripe, a flick of the finger on the stalk separates it from the vine. Effortless.
I can vouch for these as personal experience.
In my opinion/understanding - The mantra prays to the shiva, the auspicious, the one unseen but spread/felt like the fragrance (fragrance from a single source is felt all over in the room), the nourisher, may he make my separation as painless as that of a karkaTi/urvArukam (when ripe, so may I also a ripe life and painless death), but no separate from deathlessness.
Also, since every mortal body must perish in its form, I think the meaning/prayer/wish here is to conquer the fear of death, not mortal death itself. It is the fear of death that is painful.