A pufferfish spaceship is, generally, any spaceship constructed using pufferfish. The term may refer specifically to the extensiblec/2 period-36 spaceship constructed by Ivan Fomichev in December 2014, the first such spaceship to contain no period-2 or period-4 parts. (The first two or three rows might be considered to be period 2 or 4, but they are directly dependent on following rows for support.).
The pattern consists of two adjacent pufferfish puffers, plus four copies of a nontrivial period-36 c/2 fuse for pufferfish exhaust, discovered using a randomized soup search.