Space Amoeba (1970)

When a space probe crash-lands on a far-flung Pacific atoll, the craft’s alien stowaways decide to take over their new world one creature at a time. Soon, the parasitic life forms latch onto three indigenous critters — a squid, a crab and a snapping turtle — and transform them into colossal mutant monsters.
Ishirō Honda, Seiji Tani
Akira Kubo, Yukiko Kobayashi, Atsuko Takahashi, Yoshio Tsuchiya, Tetsu Nakamura, Sachio Sakai, Kenji Sahara, Yū Fujiki, Noritake Saito, Chōtarō Tōgin, Wataru Ômae, Yukihiko Gondô, Shigeo Katô, Rinsaku Ogata, Yûko Sugihara, Haruo Nakajima, Haruyoshi Nakamura
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