The overwhelming popularity of Heppoko leaves me little choice but to post this image from Issue 2 of Comic Charge.

Also, I should note that his official English title seems to be "the Great Abnormal Imo from Outer Space." Chokkaku and Ishikawa have wisely chosen not to translate imo here. It could technically refer to one of several plants in the Solenales order, but the unmarked form usually implies a satsuma-imo (sweet potato): yaki-imo (baked sweet potato), imo-yōkan (sweet potato yōkan), etc.

(So why not say "space yam" in the first place? It was a spur-of-the-moment decision to go with equivalence of markedness rather than of meaning, largely driven by superior comic potential of word "potato".)