The amoeba engulfs its prey and digests it with extremely strong acids. It's trying to get to us.
10 seconds sound clip from the The Angry Red Planet movie soundboard.
You can hear this line at 01:05:19 in the Blu-ray version of the movie.
Quote context
[...]
- Give me that suit, Tom. We'll put it in the disposal unit.
- What is your opinion of that creature?
- Now, wait a minute. Whoa. Heh. Let me in on it, Irish, huh?
- Ah, we must be safe in here.
- The amoeba engulfs its prey and digests it with extremely strong acids. It's trying to get to us.
- I wouldn't say that. Not after what we saw it do to poor Sam.
- It'll take time, but it probably can eat right through the ship.
- Well, we've got to get rid of it some way.
- But how? It can't even be touched with anything we have.
- You've experimented with amoeba on Earth. What sort of thing affects them?
[...]