The pyramid rises from a broad base to a single point, so it is read as lasting achievement, ambition and the hidden chambers of the self. Entering one is traditionally a search for old, buried knowledge.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.