No idea what this is.

[u/ImaginaryAct903]

My mom is a school bus driver and someone left this today. The four balls are a single piece and feel heavy for their size. The black case zips open and closed.

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[u/Crits-and-Crafts]

They're fidget balls. Popular with autistic kids. My daughter has this exact set

[u/Crits-and-Crafts → u/Crits-and-Crafts]

Like this set on Amazon

[u/ImaginaryAct903 → u/Crits-and-Crafts]

Solved!

[u/AutoModerator → u/ImaginaryAct903]

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[u/payloadspecial → u/Crits-and-Crafts]

Balls!

[u/JonnyGalt → u/Crits-and-Crafts]

When she gets older and want something similar, Chinese people have been using these for centuries!

https://en.wikipedia.org/wiki/Wenwan_walnuts

[u/tiptoptony]

Fidget balls, when you're bored and you just got to play with some balls

[u/wcoastbo → u/tiptoptony]

Textured balls

[u/Sh0ckValu3]

I was gonna be 100% Kegels. But maybe not.

[u/RDFozz]

Textured replacement testes for eunuchs.

[u/LordGoodBoi1]

Autism balls?

[u/RuthTheWidow]

I see the answer is fidget balls... but I would probably use these to make textures on clay! Neat, might have to look into these more.

[u/Plenty-Cattle9791]

I would guess dryer balls, but they look too small and doubtful a school age kid would be carrying them around.