What can this curved brick with square holes be used for?

Question

I recently came across this piece:

What piece is it, and how can it be used?

Answer 1

The part is Window Round 3 x 3 x 2 (73878).

It was a new mold for 2021, and one of its first uses was as windows on Andrea's House (41449).

This piece can be used on buildings anywhere you'd like a curved window. It is easy to imagine how it could have been used on earlier sets, such as the "curved" windows on the Pet Shop:

This part introduces opportunities for curved windows, but it continues to use existing window glass. It uses the 1x2x2 glass (60601):

This means that the part is also compatible with other window panes, such as the 1x2x2 bars:

These parts are paired together to create the curved window seen in Chamber of Secrets (76389):

Like most parts, there's plenty of ways to use it. It shows up as fences in Heartlake City Park (41447):

It even gets used to create a water wheel in Medieval Castle (31120):

I played around a little with this part at microscale and put together a Mars research station based around the idea of round pods: