What is this ?

[Mekong Mike]

I found this rock near a beach in vietnam. On the left side and bottom it appears to be melted stone. It must weigh about 450 lbs, i cannot get it on my motorcycle to drag it home. It's about 2 feet across. It has no seashells in it, however it does have very small stones or minerals that sparkle. It does not look like it came from the sea. It's about four hours from saigon to the north at long hai beach.
Thanks for looking.