Small, hard, hard to find testicular lump

My husband has had slight pain in his left testicle on and off for about a week.
He found a small, smaller than a pea, hard lump. It’s quite hard to find, I can’t find it myself and it takes him a little while to find it.
When touching it it feels a little sore, but his testicle pain has gotten better. He reckons it feels like it’s on a “tube” connected to the testicle rather than directly on the testicle. If that makes any sense!
If he’d not had the testicle pain he probably wouldn’t have found it, as it’s not ‘obvious’.
He doesn’t seem worried (although he knows I’m a worrier so probably wouldn’t admit to me even if he was!)
I’ve told him to get it checked out, which I think he will, but has anybody ever experienced anything like this?
Thanks!

Bumps on the tubes are generally not a worry and are usually harmless fluid filled cyts which are most common in middle aged men. Still see the doc though, but he doesn't need to stress in the meantime.