If you quickly replace the block on top of a stalagtite and randomTickSpeed is set to a high value, a middle part of it changes its thickness to "frustum"

Steps to reproduce (I couldn't provide a video because it was too large):
1. Build the structure as shown in the picture and set randomTickSpeed to 10000
2. Replace the block on top of the stalagtite quickly so that it doesn't fall down
3. Try that several times
Eventually, one stalagtite part's thickness will change from "middle" to "frustum"