Gnarantula

A Gnarantula is a cloud-covered arachnid found in Mario & Luigi: Partners in Time. The cloud hides the monster's body; when attacked, a Gnarantula's true form will be revealed. In fact, there are two types of Gnarantulas: the green, spiked Gnarantula and the orange, spike-less Gnarantula. As the cloud conceals its body, it is unwise to jump on a Gnarantula until its true form has been revealed. Otherwise, one might accidentally be damaged by the green Gnarantula's spikes. Of course, the orange variety can be jumped on. To attack, a Gnarantula will jump then jump again in mid-air, eventually falling to the ground and crushing an opponent. This attack can be countered with a Hammer strike. Gnarantulas live in the clouds high above Yoshi's Island.

The green variety is vulnerable to fire attacks, and the orange variety is vulnerable to ice.