kola2134 (Y'know what, sure. But you'll have to hide well. I'll presume that John hid himself inside an asteroid, but Sarah better pull something smart.)
As the fires go through, they seem to mostly be stopped at the first layer of armor, that is when, if one of the crew members as a last thought before the mass impacted above them due to the moment, would think. If such a think is deployed by missiles and resisted the flak that was fired from the ship during its descent, and is meant to board ships, it likely can already resist surface weaponry on said ships, or be it, ship-grade Point-defense weaponry, all of which was much more powerful than the weaponry the marines had.
The lasers were somewhat effective, they poked holes in the armor, albeit small ones, sometimes they couldn't get through the thickness of the plates. The kinetic rounds seemed to respond weirdly to the mass, it sent ripples and made the plates recoil backwards, transmitting most of the kinetic energy in form of a large shock through the amorphous being thanks to its amorphous properties. The flamethrower seemed to be the most effective weapon as it burned through the fleshy material to a certain degree, until its own fuel ran out, revealing that the creature wasn't flammable. It was a true horror that now clashed down upon the whole group like a wave, in a last few seconds of horror the marines were engulfed in the mass and then:
Peace. Silence from the guns that stopped thundering. The marines floated gently within its mass, sleeping, a deep sleep induced by the gelatinous yet fleshy being. A thick plate like a cocoon formed around them and their induced comma, as if protecting them.
Even the space-marine wasn't safe from it. The being had no problem ripping its arm off as it had enough strength to bust through some meters of steel, what it was designed to do. And so, proceeded to inject ludicrous ammounts of hormones into the space-marine.
It was now searching the rest of the ship, using its organs to sense where the rest of the crew were, as it started to rip a locked door off its hinges, luckly not the one that the rest of the crew were in, but frightening still.