Its burrowing capability is mostly an adaptation that allows them to burrow their way through body armour. They won't be single handedly devouring star ships or tanks, though in massive swarms (And I mean massive swarms, with at least several hundred parasites) they could pose a serious threat to light vehicles and possibly heavier vehicles if they were coordinated enough to attack a weaker part of its structure (If you are operating a form of walker with thin, spindly attachments to its central body, take note...) They are much, much more effective against even thick and tough organic material, tearing their way through it very quickly, individually, they would pose a threat to up to one inch of titanium, with effectiveness slowly dropping the longer they are working and after one inch their effectiveness generally begins to drop rapidly as their teeth have likely been severely damaged (Consumption of biomass will allow for regeneration of the damaged "teeth), so for their size they are certainly very good at munching away metals... Of course, its much harder if that metal is a hostile vehicle or combat drone, in which case its likely trying to kill you..

The parasite is deceptively durable, able to resist extremely high and low temperatures as well as extreme pressures, and suitable to many different enviroments. They are capable of both aerobic and anaerobic respiration and are able to survive being weighed down with over 60 times their own weight (Though when you consider how little they weigh, they could be stomped on by something with sufficient strength.) Their form is boneless, and contorts easily, being very malleable, allowing them not only to squeeze through small gaps but also conferring some resistance to pressure and weight. However, they can be taken down very easily by any species with even basic ballistic weaponry. A bullet will punch a hole through them, killing them easily if it hits their 'sack'. They are made to survive in the environment and inside the host, the mind doesn't really need them to be bullet proof if it can pump out the numbers. They are resistant against the environment, they are not resistant against sentients, who generally make weapons to kill them with. If you can break their sack then you've killed them.