diff --git a/configs/morphology/5_arms_full_fullconnected.yaml b/configs/morphology/5_arms_full_fullconnected.yaml
new file mode 100644
index 0000000..ab08e59
--- /dev/null
+++ b/configs/morphology/5_arms_full_fullconnected.yaml
@@ -0,0 +1,7 @@
+# 5 Arms Full Morphology Configuration
+# Baseline 5-arm brittle star.
+
+segments_per_arm: [4, 4, 4, 4, 4]
+use_p_control: true
+use_torque_control: false
+morph_mode: FULLY_CONNECTED
diff --git a/src/brittle_star_project/ppo.py b/src/brittle_star_project/ppo.py
index 635e7b8..79fea1c 100644
--- a/src/brittle_star_project/ppo.py
+++ b/src/brittle_star_project/ppo.py
@@ -119,7 +119,8 @@ def get_action_and_value(
 ):
     hidden_sensor = sensor_apply(params["sensor_params"], x)
     hidden_critic = feature_extractor_apply(params["feature_extractor_params"], x)
-    hidden_sensor = message_passer(params["message_passer_params"], hidden_sensor)
+    if message_passer is not None:
+        hidden_sensor = message_passer(params["message_passer_params"], hidden_sensor)
 
     debug.callback(logger.debug, f"[SHAPE] hidden_sensor: {hidden_sensor.shape}")
     debug.callback(logger.debug, f"[SHAPE] hidden_critic: {hidden_critic.shape}")
diff --git a/src/brittle_star_project/trainers/PPOTrainer.py b/src/brittle_star_project/trainers/PPOTrainer.py
index 9cbcf7c..f7c6489 100644
--- a/src/brittle_star_project/trainers/PPOTrainer.py
+++ b/src/brittle_star_project/trainers/PPOTrainer.py
@@ -514,7 +514,12 @@ class PPOTrainer:
             return jax.vmap(lambda x_in: self.message_passer.apply(p, x_in))(x)
 
         self._ppo = PPO(
-            self.ppo, apply_sensor, apply_actor, apply_critic, apply_feature, apply_message_passer
+            self.ppo,
+            apply_sensor,
+            apply_actor,
+            apply_critic,
+            apply_feature,
+            apply_message_passer if self.message_passer is not None else None,
         )
 
         self.agent_state = self._init_agent_state()