They look to be shirataki noodles, which are made from yam I believe. I haven't tried that particular brand but have tried the brand we have here in Canada. They are okay in a stir fry. They are a little on the rubbery side, but like spaghetti squash, still not pasta. Rinse them well, boil briefly, then pan fry them to remove moisture. Worth a try if you are craving pasta.
Haven't tried the noodles of this brand, but had the rice version yesterday. Very good for making things like fried rice that would otherwise be off limits and less smelly after washing than other brands. Be careful how much you eat though! These are called 'broom for stomach' in Japanese because of the high fibre! Can give you tummy trouble if you over do it.
The rice versions are also worth a try for a quick meal, and good for stir-fried rice. I find my local Holland & Barratt very expensive so I bought some konjac rice from a health food shop to see what it was like - I'd rather see a packet 'in the flesh' before buying blind online and my nearest Chinese supermarket is over 50 miles away - and you might be able to find a cheaper version locally. There are threads on this as @wiflib mentions, but critical advice? Wash the smell away first! (It was an eye-opener, literally, for me....!)