A pufferfish spaceship is, generally, any spaceship constructed using pufferfish. The simplest would be to delete the puffed blocks with middleweight or heavyweight spaceships. The term may refer specifically to the extensible c/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. Nico Brown found additional puffership spaceship variants two days later. Chris Cain found a 60-glider synthesis of an elongated pufferfish spaceship in February 2015.