Lump on my dog's testicle

Hi I noticed a lump on my pocket bullies testicle . It's very prominent. Hes a healthy 3 year old. It's not swollen or red or painful. But now that I took pictures it looks like there could be two of them.  Should I be worried? Is this common? Thank you.

Dear KiwiBaybee This is one of my favourite questions - not least because I find it encouraging that people are checking their dogs' nads and are willing to ask when they need help with something referring to testicular anatomy - that's awesome.  When I first qualified, it was rarely the case.  But secondly, I like it because it's a question that is easily answered.   Dogs' testicles each come with two lumps - the testicle (the big one that makes sperm) and a much smaller one, almost D-shaped in cross-section, called the epididimis.  (I say almost D shaped because in real life the upright stick isn't straight; it's concave to fit against the surface of the testicle).  This is the start of the tube that travels away from the testes and goes off down the penis; the tube that sperm travel along to 'get out.'   There ought to be two of them - one for each testicle - and they ought to be equal in size.  (Sometimes one or other becomes inflamed or infected, so if they are different from one another or more prominent than usual, please see your vet).