OK, so it goes like this:
- there's a team of space marines that crash land/arrive in an underground cave system
- they are in a ship. the action takes place inside and around the ship, in the cave
- they fight a series of enemies that they consider to be alien, spider looking creature, made of flesh and robotic parts
- they're pretty hard core, fighting the creatures
- one of them used to be an athlete, a footbal player back on Earth
- while fighting the creatures at one point they realize that the creatures are actually other space marines that were there for hundreds of years protecting something
- the creature/space marines have gotten in that state because they regenerated/healed using an UV system repeatedly and changing their form to better suit their environment but in the meantime forgetting everything about their lives
I read this sometime around 2011. The book seemed fairly new, like on of those fresh authors publishing for Kindle on Amazon.
It was written in English, by an American author.
I'd really love to re-read this and just can't remember anything else about it.