Well, yes it is. As you see, munchlax is a baby Pokemon, and you need to breed a snorlax holding the full incense in order to get munchlax. So yes, it is possible to get a snorlax egg. Hope I helped!
If you need fissure, here's how to get it:
>1. male Stunfisk with Fissure
-breed with female Lapras
2. -resulting baby Lapras must be male
male Lapras with Fissure
3. -breed with female Snorlax