Cursor

The Cursor is a block introduced in Java Edition 20w14∞ with an animated texture that changes its color every second, toggling between lime and black concrete.

Obtaining
Cursors are available in the creative inventory, and naturally generate in the “terminal” dimension.

Breaking
Cursors require a pickaxe to mine.

Natural generation
The block naturally generates in "terminal" dimension as the blinking "_" next to a "C:\" made of lime concrete. It appears to be cycling between black and lime Concrete in appearance, which is what the rest of the "terminal" dimension is made of.