Put the summary of the bug you're having here

What I expected to happen was...:
When placing water inside mangrove propagule,placing lava above should mix with water into stone.

What actually happened was...:
lava does not mix from above with the water and simply touches it.

Steps to Reproduce:
1. plant mangrove propagule
2. place water on mangrove propagule
3. place lava above mangrove propagule