[Hitman]

I think there are also fish swarms, and IIRC Sub Command also simulated false contacts, which were just to be considered water turbulences and such.

I believe you could add any new item you want to the game by creating a 3D model (Even if a hugely simplified one, even an invisible one), making it a biological entity and giving it a sound. But others more experienced in working with the databases will probably know best.