I have already statted this xenomorph for Stars Without Number; here it is with Classic Traveller stats.
Pouncer, solitary or clutch (2d6), 25kg, 12/7 hits, as Cloth, "Teeth" (actually, a beak at its "base") 2D, A if surprise, F if surprised, S1
The Cave Squid is one of the larger predators on a dry, cold, dusty world on the edge of known space. Exceedingly hardy like all native life-forms of that dust-world, the squid can weather the biting dry, cold air and filter out even the worst dust-storm, requires little water and may lie half-dormant for a long period in wait for prey. Its natural habitat are caves and rocky outcrops, from which it hangs in wait for prey; in modern times, it also has an annoying habit of infiltrating abandoned or seldom-used buildings, then attempting to eat anyone who tries to reclaim them. A hardy animal, the Cave Squid hitched a ride on many an unknowing free-tader outbound from its homeworld, and by now they have adapted well to most "shirt-sleeve" and marginal environments all over known space as an invasive species.
The cave squid hangs from a ceiling - cave or building - by its muscular "foot" placed at the top of its body. When motionless, it can look like a stalactite, by holding its tentacles stiffly under itself, or like a lump of rock, spreading its tentacles so the membrane between them covers its body. Its shell and skin usually resemble limestone, though a cave squid can change its color to match almost any type of stony background. This how it ambushes prey - when a creature enters its cave (or abandoned building), A Cave Squid is about 120cm long from the tips of its tentacles to the top of its head and weights approximately 25kg. Once the tough outer hide is peeled, the innards of this creature are much softer, and are considered a delicacy on its homeworld and on several other worlds all across known space.
The Cave Squid uses echolocation to detect its prey, and thus can "see" perfectly even in total darkness. When in hiding, it enjoys a total +3 DM to surprise (Pouncer DM already included); if the Cave Squid attacks an unsuspecting victim, it enjoys a free round of action when it can attack before the victims may act themselves. On a successful attack, it may attempt to grapple and strangle its victim on 6+ on 2d6 (DM -2 if the victim has STR 8+); if it succeeds, it grapples its victim, immobilizing it. On each subsequent combat round, the victim is allowed a roll of 8+ to get free (DM +2 if STR 8+); if he fails, the Cave Squid may constrict him, doing an automatic 1D damage (the Cave Squid may roll to attack him as well as its main action at the same round).