Dreams featuring animals, especially in unusual or unsettling scenarios, can often reflect our subconscious thoughts and feelings. In your dream, the tortoises trying to bite you and their strange physical characteristics might symbolize feelings of vulnerability or being threatened in some area of your life.

1. Tortoises: Traditionally, tortoises represent wisdom, protection, and stability due to their hard shells. However, in your dream, their aggressive behavior suggests that you might be feeling overwhelmed or attacked by something you usually perceive as stable or safe.
2. Surrounding your mattress: A mattress often symbolizes rest, comfort, or personal space. Being surrounded by these tortoises could indicate that there are stressors or worries invading your personal space or peace of mind.
3. Distorted shapes: The unusual shapes of the tortoises may point to a situation in your life that feels out of balance or distorted. It could be a relationship, work situation, or even your perception of self that feels off.
4. Baby tortoise: The presence of a baby tortoise might suggest new beginnings or responsibilities that are burdensome. If you associate the baby with growth, it could indicate that there are new developments in your life that you feel are overwhelming.
5. Rhinestone-covered tortoise: This could symbolize superficiality or the idea that something may look appealing or glamorous on the outside but has a deeper, more troubling nature underneath.

Overall, this dream may be urging you to reflect on areas in your life where you feel threatened or uneasy. Consider what might be causing you stress or anxiety and how you can reclaim your personal space and peace of mind. It may be helpful to address these feelings directly in your waking life.