Spiny Tromp

A Spiny Tromp is a large, spiked orb with a surly face; it bears a small resemblance to a circular Thwomp.

Spiny Tromps first appeared in Paper Mario, where they were found inside Mt. Lavalava; in a corridor of Mt. Lavalava, a Spiny Tromp would appear to try to crush Mario; Mario would need to use Bow's intangibility powers to avoid the Spiny Tromp.

Later, another Spiny Tromp, after having its path cleared by Mario and his Ultra Hammer, would roll haphazardly towards Mario. Mario would once more need to use Bow's ability to make himself intangible to avoid the rolling Spiny Tromp.

Unfortunately, the Spiny Tromp would continue to roll and crush the nearby Kolorado, injuring him severely; the Spiny Tromp would then blast its way through a nearby wall, clearing Mario's path before embedding itself in a wall.

Despite their absence from Paper Mario: The Thousand-Year Door, several Spiny Tromps appeared in Super Paper Mario (in which they gained a name, since there was no given name in Paper Mario) as obstacles in the Yold Desert and Underwhere Road, where they are shown to come in varying sizes. In order to dodge these Spiny Tromps, Mario would need to Flip, which reveals that Spiny Tromps are actually rather thin and composed of three layers of a spiked, cardboard-like substance.

A small sub-species of Tromps, referred to as Spiky Tromps, also appear later in Super Paper Mario, in Yold Ruins, where they would often act as obstacles.

Statistics (Super Paper Mario)
Tippi's Tattle: This Spiny Tromp loves to roll down hills and over unlucky pedestrians... You can't beat it...  You can only avoid it...  It rolls down the hill fast, but I know Mario can find a way to avoid it...

Trivia

 * The term "Tromp" is likely derived from "trample," referring to their attacks, and "Thwomp." However, "tromp" actually is a slang word that can mean either "trample" or "ultimately destroy."
 * Spiny Tromps seem to be related to Tap-Taps because of their round shape and spikes.