i was messing with snapshot 13 w 19 a and noticed i could suspend mobs so i started with a pig then a sheep then a wolf ..... Then i tryed a horse . I tryed everything to get the horse to stay puting a plat form and breaking it under it pulling it up shoving it off the post. Nothing would work.......
So then i tryed a squid ..... And i pulled the squid up so fast yet this horse i couldn't get to go up.

After this i Decided mobs must have weight.