Warm greetings @vanna!
An entity associated with a big animal, aging or time, and Earth energy, hmm…
Here a few guesses you might consider:
- Chronus, the God of Time, comes to mind for aging and earth energy
- Hecate, a Goddess of Magic and Death, is often depicted with a large dog
- Hel/Hela is a Norse Goddess of the Underworld who is sometimes seen with a wolf
- Durga is a Hindu Goddess of both protection and destruction who is often seen with her lion
- Thanatos is a spirit or deity who is the personification of death (although his animal is a small butterfly)
My personal go-to answer for finding more information about a deity/spirit/entity is to pick up my tarot cards- they can reveal a lot about the identity of a being, as well as offer ways you might connect with or contact them 
Here’s a spread made just for that purpose! You can use tarot cards (here is a free tarot deck if you don’t have your own), oracle cards, or even regular playing cards to get answers:
Whatever you choose to do, I hope you are able to connect with and learn more about the mysterious visitor! Good luck and blessed be 