Smooth, glassy lava is called pahoehoe (pronounced "pa-hoy-hoy").

Here's why:

* Pahoehoe is a Hawaiian word that describes the lava's smooth, ropy, or billowy surface.

* This type of lava is characterized by its low viscosity, allowing it to flow easily and cool slowly.

* As the lava cools, its surface can form a glassy crust that can be very smooth or have a rope-like texture.

Let me know if you have any other questions!