diff --git a/explore_120 b/explore_120
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/explore_120
@@ -0,0 +1 @@
+
diff --git a/explore_120cell.js b/explore_120cell.js
index af0a0de..975287a 100644
--- a/explore_120cell.js
+++ b/explore_120cell.js
@@ -304,26 +304,67 @@ function find_adjoining_5cells(cell120, all5, v1, v2) {
 
 
 
-function tetra_600_cell(cell120, all5) {
-    // find a tetrahedron on one of the 600-cells
+function tetras(cell120, all5, v) {
+    // given a vertex v, find all of the 600-cell tetras it's on
 
-    const v1 = cell120.nodes[0];
-    const n600s = neighbours600(cell120, v1.id);
-    const v2id = n600s[0];
-    const n2600s = neighbours600(cell120, v2id);
-    // find mutual neighbours of the first two
-    const mutuals = n2600s.filter((nid) => nid != v2id && nid != v1.id && n600s.includes(nid));
-    // find mutuals which are mutuals of each other
+    const n600s = neighbours600(cell120, v.id);
+    // need to find all sets of three neighbours which are neighbours: there
+    // should be 20 of these because they're faces of an icosahedron
+    console.log(v.id);
+    const tetras = new Set;
+    for( const v2id of n600s ) {
+        // find mutual neighbours of the first two
+        const n2600s = neighbours600(cell120, v2id);
+        const mutuals = n2600s.filter((nid) => {
+            return nid != v2id && nid != v.id && n600s.includes(nid)
+        });
+        for( const nm of mutuals ) {
+            const nnms = neighbours600(cell120, nm);
+            const mutuals2 = nnms.filter((nid) => {
+                return nid != nm && nid != v2id && nid != v.id && mutuals.includes(nid)
+            });
+            for( const m2 of mutuals2 ) {
+                const t = [ v.id, v2id, nm, m2 ];
+                t.sort((a, b) => a - b);
+                const tstr = t.join(',');
+                tetras.add(tstr);
+            }
+        }
+    }
+    console.log(tetras);
+}
+/*    // find mutuals which are mutuals of each other
     const m0 = mutuals[0];
     const mn = neighbours600(cell120, m0);
     const mm = mn.filter((nid) => nid != m0 && mutuals.includes(nid));
     return [ v1.id, v2id, m0, mm[0] ];
+}*/
+
+function str5cell(c5) {
+    return ["1","2","3","4","5"].map((l) => String(c5[l]).padStart(3, '0')).join('-');
+}
+
+function tetra_sets(cell120, all5, tetra) {
+    // given a tetrahedron on a 600-cell, find the sets of adjacent 5-cells on
+    // all of the pairs
+    //  this is ass-backwards. Need to find tetras on the other 4 vertices of a 5-cell
+
+    const vs = tetra.map((tid) => cell120node(cell120, tid));
+    const pairs = [[0,1], [0,2], [0, 3], [1, 2], [1, 3], [2, 3]];
+    for( const p of pairs ) {
+        const v1 = vs[p[0]];
+        const v2 = vs[p[1]];
+        const c5pairs = find_adjoining_5cells(cell120, all5, v1, v2);
+        console.log(v1.id, v2.id);
+        console.log(c5pairs.map((p) => str5cell(p[0]) + "    " + str5cell(p[1])));
+    }
 }
 
 const cell120 = POLYTOPES.cell120_inscribed();
 const all5 = gather_5cells(cell120);
 
-const tetra = tetra_600_cell(cell120, all5);
+const v1 = cell120.nodes[0];
 
-console.log(tetra);
+tetras(cell120, all5, v1);
+tetras(cell120, all5, cell120.nodes[1]);