[lemonstar]

They look like bits of broken teeth and are just as hard - I only really buy Conference pears so I don't know if it is specific to that variety or not - I doubt it. I certainly want to avoid biting them as they are so hard - I've found some that are a good 2mm in size - they are quite irregular in shape.

[mumofstig]

When pears are stressed they develop more Sclereids aka stone cells, they may not do the same thing in a normal year. So fingers crossed for this year...

[jaydig]

I had this problem with my pears in 2018, I think it was the extreme heat, although I did try to keep the trees well watered at the base.  Hopefully it won't happen this year.